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Volume Shadow Copy For Linux?
An anonymous reader writes "I was asked to manage a number of Linux servers at work. I would like to use volume snapshots to improve my backup scripts and keep recent copies of data around for quick restore. I normally manage Windows servers and on those I would just use Microsoft's Volume Shadow Copy for this. I tried Linux LVM snapshots, but most of the servers I manage run regular partitions with ext3 file systems, so LVM snapshots will not work. I found some versioning file systems out there like ext3cow and Tux3. Those look interesting, but I need something I can use on my existing ext3 file systems. I also found the R1Soft Hot Copy command-line utility, but it does not yet support my older 2.4 Linux servers. What are you using to make snapshots on Linux?"
Nilfs will have those things, but you`ll have to wait till its production ready.
Linux servers don't get backed up, they only get migrated to new hardware every five years. (BSD is the same, except for the second part.)
You will have to migrate your servers with plain ext3 to LVM-based ext3. Short term pain for long term gain.
Hey, IRC called, they want their asshole back.
"does not yet support my older 2.4 Linux servers"
So upgrade your servers to a supported release instead?
-- Terry
LVM snapshots only work fine if you are using LVM. I think the OP uses "regular partitions" to mean no volume manager in use.
I use them on ext3 with no problems. It's true that very early on there was a problem with them and journaled filesystems, but that has long since been solved.
LVM snapshots work on a block level and don't care about the filesystem. A snapshot of any data in a logical volume should work fine, even if it's not a recognized filesystem.
A nice use for this is using a read/write snapshot to try different strategies for recovering a broken filesystem.
How many servers and what is the approximate amount of data that you need to backup?
I think you might have misread what he said.
ext3 file systems on regular partitions wouldn't be able to use LVM snapshots, because, well, they're not running on LVM volumes.
Nevermind, I was the one that was confused. You currently have ext3 fs that are NOT on LVM. In the future, choose LVM.
I will admit that I have not tried it on Linux, but zfs is the best of the next gen filesystems. It does cryptographically assured reads and writes (remember that transitory undetected disk malfunctions occur at a rate of ~1/TB of data), it can snapshot changes, it fricken slices bread. If it had a gender, I would probably marry it (well, I guess I can date it for a while and see how things work out). http://zfs-fuse.net/
If people can connect to one another even the smallest of voices will grow loud.
--Serial Experiments Lain
Thanks for elaborating, we will try your suggestions and report back.
RSnapshot uses a clever blend of rsync + hard links to do what you want... you can store many incremental backups in just a little more space than a full backup. you can run rsnapshot on a backup server with lots of disk space, and all you need to expose on your target machines is SSH.
you'd create "backup" users on all the target hosts, generate a PKI key pair, and put the private key on your backup server. put the public key in the "backup" account on each target machine so the backup server can securely login without a password. then you just set up rsnapshot to log into your targets and it will use rsync-over-ssh to pull the data.
http://rsnapshot.org/
Oh shit! I forgot to click "Post Anonymously"...
Since the situation is so hobbled (Old Linux kernel, no LVM) about the only thing you will be able to do is learn to use hardlinks. The ext* filesystems support them but you will have to manage them yourself (cp -varl /source/* /destination/version). Yeah it's a huge hack, but unless you can actually fix the problem, it's about your only hope.
... And so it comes to this.
If you have backups, then moving to LVM is obviously the way to go if you desire snapshots. The others options are short-term hackery, LVM was designed from the ground up to do such things. And Ext3 has nothing to do with the price of butter.
To clarify, let me rephrase your question for the other way around
"I was asked to manage a number of *Windows* servers at work. I would like to use volume snapshots to improve my backup scripts and keep recent copies of data around for quick restore. I tried Windows Shadow Copy, but most of the servers I manage run MBR partitions with FAT file systems, so Shadow Copy will not work. I found some versioning file systems out there... Those look interesting, but I need something I can use on my existing FAT file systems. I also found --random freeware--, but it does not yet support my older Windows NT 3.5 servers. What are you using to make snapshots on Windows?"
Except, in that case, it makes more sense because the filesystem is the determining factor, not the volume management. If you have LVM, it doesn't matter what the underlying filesystem is, really. Stop faffing about - if you have a server, with backups, that you need snapshots on, take the hit and wipe the drives to a config that supports that... while you're there upgrade that damn kernel already. If nothing else, it will test that the backups you're making are actually worth the effort. It's like complaining that 95 on FAT16 doesn't support Shadow Copy. If you absolutely *can't* take those servers down, or am unable to restore your backups to another machine for testing such changes (whether because of compatibility, software licensing and/or bad backups), you have bigger problems than some random desire for a feature you don't actually *need* at the moment.
Have you looked at rsnapshot?
It's based on this article:
http://www.mikerubel.org/computers/rsync_snapshots/
Isn't that like complaining that your FAT32 partitions in Windows are not supported by Shadow Volume Copy then?
I think there's a bit of double standard here in the question. The OP is stating that they want to use a feature on an older server (2.4 kernel?) that isn't available unless you update the server, reformat, or what have you. The same applies to a Windows environment.
I think the question is mis-guided. They should be asking for a SVC like feature for kernel 2.4 and ext3 systems.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
rsnapshot has no actual snapshotting functionality. It's just a (very useful) wrapper around rsync that takes care of de-duplication. While making a rsync/rsnapshot backup, files on the system can still be changed.
For example: A LVM snapshot would give you a consistent MySQL dump if you're using innodb. Rsync/rsnapshot does not.
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If they are indeed regular partitions, he can't use LVM snapshots. However, the best solution is to convert from partitions to LVM volumes. It's a little effort to do so, but switching is worth it. Second best is to wait until btrfs is more usable. As a ZFS user, I can say that filesystem-level snapshot are much nicer than LVM snapshots in lots of ways.
Another possibility is to abuse hardlinks. You can create a copy of a directory with cp -al, and then overwrite (not modify) files on the original, you'd have copy-on-write copy. If you make your backups with rsync, you can configure rsync to never write to existing files and always overwrite, then use cp -al each weak or day, to store "incremental" backups for weeks and maybe more. I personally found this solution nice, but then I installed Solaris on the backup machine and used ZFS snapshots which do the same safer, simpler and more efficiently. If the backups are stored on a separate machine, switching it to Solaris is an option.
Another thing that can be done is to keep the LVM snapshots on a separate machine, and leave the current partitions as they are. It can be done with rsync, or a drdb device can be used to sync with the server (it can be created without reformatting the partitions, but you still need to make some changes like shrinking and/or moving the data, which might destroy the data if you don't know what you're doing).
Replace: "Volume Shadow Copy" and "VSC" respectively in my post above. Sorry.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
Only works if the partitions don't change while you are copying them. The big advantage of using LVM for this is that you can create snapshots on a live system, without resorting to remounting the partition read-only (and all the problems that will cause).
But really, those are his only options. If you insist on using plain ext3 and won't add a layer of between the FS to allow for this, then you have no choice but to freeze the partition while doing a volume-level back up.
There are Enterprise Linux distributions that are both supported and still run 2.4, though not for much longer. Not everyone runs Ubuntu.
"I use a Mac because I'm just better than you are."
Most people just use rsync for backups. LVM is a lower level then the file system... you create a storage pool and then create filesystems on top of that. If you really want to use LVM snapshots you would have to recreate your filesystems, which I gather you would like to avoid. There are lots of options for filesystems that include versioning in some form or another. If you do want to choose one of these filesystems, find the Wikipedia article for any filesystem and down at the bottom will be a list of filesystems you can explore. If you just want to snapshot the entire partition, you can remount it readonly and use dd to copy the block device to a file (this will take up space for every byte, including unused space unless you compress it). I congratulate you on the opportunity to work in a unix environment. Please don't get discouraged because it is different, it really isn't that hard to learn, and many people would say it's easer. Google and Wikipedia will be indispensable.
Knowing where to start on this is a bit of a miffing point.
First: upgrade your shit. 2.4 kernel systems? Are you running Redhat 6? You know, from the turn of the millennia.
Second: upgrade your shit. Really,
Third: if your kernels are that old and you're using these machines for file storage/backup, chances are the hardware needs to be replaced before you even consider considering messing with them. Seriously: this stuff is ancient. Even Debian hasn't had a 2.4 kernel in 5+ years, I think.
Third: you can do what you're trying to do with rsync 'snapshots'. It works very well, failing filesystem level support. If you're sharing data over samba, this makes it easy: just put a '.snapshot' dir for these 'temporary' backups in their $HOME and hide dotfiles. Then make sure rsync ignores .snapshot. (Of course, there are other ways to do this.)
rsync snapshots (and here).
There are other sources of information out ther on rsync snapshots. There's also rsnapshot.
Chances are you'll have to upgrade before this stuff even works for you, though.
~/ssh slashdot.org ssh: connect to host slashdot.org port 22: too many beers
People expect a snapshot to be immediately usable and reliable, however in practice a state of device, even if synchronized with filesystem through its transaction is not a state of all data -- some data may be in buffers, prepared to be written, and rebooting into a restored filesystem may require some cleanup of such state. In particular, SQL databases are completely unsuitable for this kind of backup (this is why they have their own backup and transaction log handling procedures), and database-like applications such as mail servers, may require reindexing.
However for purposes other than those applications, file-level backup is entirely adequate, so utilities like rdiff-backup end up providing more functionality than complicated snapshot-handling procedures -- incremental backups for subtrees, readable trees in backup media, etc.
It also should be noted that backups should not be used as a replacement of package management -- on Linux anything installed through a package manager can be uninstalled through it.
Contrary to the popular belief, there indeed is no God.
You currently have ext3 fs that are NOT on LVM. In the future, choose LVM.
The choice isn't that simple. LVM comes with its own complications, including a tendency to get volume offsets "wrong" so the file system data doesn't align nicely to RAID stripes. This is not good for performance.
Also, LVM has only recently acquired barrier support, and the combination of no barriers + write cache can be quite dangerous if power is lost. Even battery backed cache won't save you if you use a journalling file system (and everybody does these days) because request ordering isn't guaranteed.
I haven't touched Solaris since it had a 2 in front of its version number, but I must admit that I suffer from ZFS envy.
Finally! A year of moderation! Ready for 2019?
I'm troubled why people still run 2.4 server. I remember the time when I was reluctant to upgrade to 2.6, and I used prefer the older 2.4, which felt more comfortable than 2.6, regardless of how tempting the new changes sounded. But now I don't see any reason I would run this anywhere, even my router runs 2.6. Especially on newer hardware, 2.4 is really really too old.
I know there are people who probably still run Linux 2.2, but that are probably systems that are running some task well enough to require any changes, and leaving them as they are is the best. Servers are usually not like that. They need security updates, upgrades to catch up with the times, and many other changes required by the circumstances (for example, adding snapshot abilities, for which some person asked recently on Slashdot). Most production servers are not systems that you just leave running, so upgrades to the kernel are also expected and highly recommended. Not to mention that most recent distributions require 2.6.
Take a look at rdiff-backup.
rdiff-backup backs up one directory to another, possibly over a network. The target directory ends up a copy of the source directory, but extra reverse diffs are stored in a special subdirectory of that target directory, so you can still recover files lost some time ago. The idea is to combine the best features of a mirror and an incremental backup. rdiff-backup also preserves subdirectories, hard links, dev files, permissions, uid/gid ownership, modification times, extended attributes, acls, and resource forks. Also, rdiff-backup can operate in a bandwidth efficient manner over a pipe, like rsync. Thus you can use rdiff-backup and ssh to securely back a hard drive up to a remote location, and only the differences will be transmitted. Finally, rdiff-backup is easy to use and settings have sensical defaults.
I can confirm that rdiff-backup is indeed easy to use.
The double standard being that the Linux servers wouldn't need updated where the Windows servers would. There's an update that has to happen to support the feature. Linux is not immune to this (though it would likely do the update without a total rebuild opposed to Windows.)
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
Funny... I read this question while browsing /. during lunch. Next in line was Linux.com which had a link to an article on Next3: ext3 with snapshots.
Here it is: http://www.linux.com/news/software/developer/317784-next3-ext3-with-snapshots
Seriously, what is wrong with dump(8)? It works on ext3. I use it on FreeBSD. It takes snapshots to do the dump, so you can shutdown your database, start the dump and then immediately start your database again. Of course you have to backup the entire volume, but still...
With judicious use of --link-dest rsync can do this for you without having to use cp at all.
Can you give us an example?
The obvious one is Redhat. RHEL 3 is the newest version to still use a 2.4 kernel. It may still be supportes, but that expires October of this year, so the OP should already be getting ready to upgrade.
Um... I'm not really following anything you're saying.
Kernel 2.4 supports LVM, he just isn't using it.
Thankfully, Linux is not nearly as complicated as Windows. Every time I've messed with Volume Shadow Copy it's turned into a huge headache. Doing similar functions on Linux just work right out of the box. I'd suggest anything that uses rsync, or you could use rsync directly. I use rsync which can synchronize gigs of data over the network, and is smart enough to parse partial sections of files. It's amazing and very efficient. Windows has nothing that even touches this, that I know of.
In case you hadn't realized this, It is possible to tell people to migrate to LVM without calling them names.
Need a Python, C++, Unix, Linux develop
Just upgrade your kernel using a manual build of the 2.6 kernel.
Also install static versions of the modutils ( insmod, modprobe, etc )
Use an external ( a machine with decent software ) for this so your compile doesn't break.
I have done so in the past and it works fine. ( and plan an update for those machines, anything with 2.4 is way to old... )
After that you can just use R1Soft hot copy,
http://www.r1soft.com/tools/linux-hot-copy/
This program is free ( as in beer ) to download and works with every block device.
You can even write to a block device if you really need to.
Their commercial offerings are pretty good as good. ( and DO work with the 2.4 kernel )
We use it here at work.
I heard btrfs supports something like this as well.
Any way, good luck!
Dump the disks to a virtual image, virtualise the machines and then you can snapshot away to your hearts content. Be it via the virtualisation tech, or the host's file systems.
However, as already said, if you're still running 2.4 kernels, you're well over-due an upgrade/migration to newer software AND hardware environments. Why not combine both suggestions?
Understandably, uptime is really golden, but everyone understands that you have to upgrade and/or maintain systems at some point.
I tried Linux LVM snapshots, but most of the servers I manage run regular partitions with ext3 file systems, so LVM snapshots will not work.
They have, presumably, tried and failed. It could support it, but it would have to be installed, updated or something to get it to work. There's something they're not doing on an old server that needs to be changed to support the feature they want. I was pointing out how this is not exclusive to the Linux servers.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
He isn't complaining. You seem to be responding to his mentioning that "he knows how to do this on Windows" , by interpreting it as "Why is Linux so broken that it can't do a simple thing like that?" This isn't a Linux versus Windows thing. This is a Windows user, migrating to Linux and wants to know how to accomplish something. Constructive answers are more useful in such cases than getting defensive by alleging hypocrisy and double standards.
Entia non sunt multiplicanda praeter necessitatem.
I'm troubled why people still run 2.4 server
They fit in well with his other servers, still running Windows 98 Advanced Server Edition.
But seriously, migrate to LVM already.
Money for nothing, pix for free
Works nicely. I use it for backups over the net. One very nice feature is that it does is reverse diffs, i.e. the nearer to the present time, the faster you get files restored. You also can remove older diffs without any fuss.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
You are getting hung up on the choice of words.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
Why does Linux still lack this functionality?
Since the early 1990's Novell has had the ability to "Salvage" deleted files and even maintained a near limitless amount of previous versions with a Copy On Write functionality. It still exists, even on Linux in their NSS(Novell Storage Services) Volumes.
Microsoft finally got on board when their Server 2003 product implemented Volume Shadow Copies. This isn't nearly as good as Novell's implementation but, it was better than anything Microsoft had previously offered.
The original poster did mention etx3cow, which offers an awesome feature set. But, etx3cow has been "under development" for a long time without ever catching on.
Ext4 has recently been incorporated into the Linux kernel and there just isn't any excuse for its lack of a Copy On Write version history. Yet here we are, in 2010, yet again answering this question without any good answer. Linux should have a standard Copy On Write file system a long time ago. Its continued absence is shameful.
ext3cow should be merged into ext4 yesterday!
http://www.symantec.com/business/storage-foundation-basic
ZFS and BTRFS, btrfs is included with Fedora 13 (maybe 12 too).
ZFS is found here http://wiki.github.com/behlendorf/zfs/
I am the unwilling control for my Origin.
Isn't there some upgrade path to convert "old" partitions to LVM partition? Just like windows supports upgrading to dynamic partitions and FAT32 -> NTFS conversions.
Yes, you always need a backup, but having a backup + doing inplace upgrade is far more convinient.
that's not as much fun.
Do you even lift?
These aren't the 'roids you're looking for.
Every time I've messed with Volume Shadow Copy it's turned into a huge headache. Doing similar functions on Linux just work right out of the box.
What are you talking about? Volume Shadow Copy(VSC) is a simple checkbox to enable it and it works! Two snapshots per day by default. Users can restore previous versions directly from their workstations with a right click, select, OK. Or, with newer versions of Windows, drag the desired version from the VSC window to where ever you want it. How is that complicated? How could you screw that up?
Meanwhile, on Linux... Write a bash script with arcane rsync arguments, create a cron job for the script, ??? Does it work as desired/expected or do you have to debug your script, cronjob, permissions? Where are the backups? How do you restore them? How do you maintain permissions and access control, especially with users that are not working local to the machine?
Here's some more information for the deluded. Windows has it's own kind of rsync. It's called Robocopy and it does almost all of what rsync does, including maintaining Windows user information and ACLs, an area where rsync fails miserably in Windows environments. But, the built in Windows features like VSC and Distributed File System(DFS) replication make the use of rsync/robocopy painful, pointless and superfluous.
If a single checkbox is a headache for you, I don't see how rsync can possibly be less so.
I have scrolled to the bottem and replied after a scrolling skim. No answers for this guy yet? Just vague debate. No "use either a,b,c,d,or e".
Thats telling.
I am in this guys situation at work.
In post Patriot Act America, the library books scan you.
This is clearly the definitive answer for this article.
We can all stop posting now.
Can you elaborate on how LVM gets volume offsets "wrong" and it's impact on RAID performance? I've never heard of that before. Not saying you're wrong, it's just news to me.
Also, IIRC Solaris still has a 2 in front of it. Ie, Solaris 10 is really Solaris 2.10, and is simultaneously SunOS 5.10. They have retarded naming conventions. Oh well, Oracle can only fsck it up further...
ZFS does rock btw, we've got about 80-90TB (guesstimate) spinning with ZFS right now. Our thumper has 32.5GB alone, and another HP box running x86 Solaris has 45.3TB. There's others, but not as big as those two. ZFS really does make it a breeze to manage that much storage.
Volume shadow copy might not be doing what you think it is. I know it makes a big file, but restoring a snapshot has never worked as expected.
It sounds like you are just trying to keep an old dinosaur alive. Reboot with a live cd and make a snapshot of the old dog.
dd if=/dev/hda conv=sync,noerror bs=64K | gzip -c > /mnt/sda1/hda.img.gz
That applies to Windows partitions too. It's faster and more reliable *restore* than Volume Shadow Copy on identical hardware. You can also move the Old Dog onto somewhat newer hardware.
gunzip -c /mnt/sda1/hda.img.gz | dd of=/dev/hda conv=sync,noerror bs=64K
You will need to check the disk (fsck) before booting the restored partition.
If you have a say in your priorities, it's time to migrate the services off the Old Dinosaur onto another server with an LVM disk and vaguely modern distro.
http://www.maxineudall.com/2010/02/should-economists-be-sued-for-malpractice.html
Perhaps you are making this more complex than it has to be. I've had zero success simply copying the files and filesystems from a Windows server to backup and then being able to restore anything but data -- you can't reinstall a Windows OS from the moral equivalent of a Linux "cp -R" command. Linux, however, does not share this feature. You can -- and I have -- use rsync or tar to copy the entire filesystem off of a Linux machine to your backup device, then restore an entire machine -- data and OS. The only caveat is that you will need to partition the disk on the replacement machine to match the partitions on the original machine, or else you will need to modify /etc/fstab to reflect the new partitioning scheme.
/backup directory. Then on the servers you manage, have them run "rsync -av / rsync://rsyncserver.example.com/backup/rsyncclient.example.com/" (where you replace "rsyncserver.example.com" with the name or IP address of your rsync server and "rsyncclient.example.com" with the name of the client you are trying to back up).
So what I do is build a backup server with a huge disk array, big enough for all the data on all the machines you manage, or at least for all the machines you want to write to this backup server. Configure rsync.conf to have a
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
Our thumper has 32.5GB alonep>
Did you mean 32.5TB, not GB?
"Can of worms? The can is open... the worms are everywhere."
Indeed. I've done so, and documented it:
http://www.tolaris.com/2010/05/06/moving-an-existing-backuppc-partition-to-lvm/
People smarter than me documented a way to move the data, live, even when the partition is nearly full. See the comments there.
This might be a bit extreme and would require some infrastructure re-org, but you could use virtualization with VMWare ESXi or XenServer to snapshot your entire box. The software is free and the scheduling is pretty robust. It doesn’t directly help with the restore of individual files, but hell, you could restore entire servers independent of your production servers and pull the files that require restoration. I know, it’s a pretty roundabout solution, but, of course, server virtualization provides all kinds of other benefits beyond this. Plus, it wouldn’t matter what kernel you’re running.
Reading through this thread has brought back the memories of when I first started using Linux. There is a subset of Linux users who seem to think that acting like a giant douche bag will help people adopt the platform.
Don't get me wrong, I've found that there are some amazing people in the Linux community that are more than willing to help out someone genuinely willing to learn, but there still exists this subset of assholes that seem to think ridicule, and basically acting like a dickhead makes them superior. If you're one of those people get over yourself. Linux would be better off without you!
ZFS is available as a user space filesystem (FUSE) and has lots of goodies including snapshots and snapshot replication for off-box disk-to-disk backup. It's got a much better feature set than LVM/ext3. I've used it and it seems stable - I've even imported and exported Zpools between Linux and Solaris without problems.
You can try to build it from source if not available for all your distros - not sure if it will compile on the 2.4 kernels though.
You are not going to find something you can 'drop on top of' a bare EXT3 filesystem and get robust, modern features like snapshots w/o some data migration.
You could also think about migrating these old physical servers into VMs and snapshot using the facilities available in the hypervisor (eg VMware or Xen).
You could also setup an NFS server or a NAS box with snapshots and migrate your data there, leaving the OS/apps to run via NFS mounts: OpenSolaris has NFS; Nexentastor, built on OpenSolaris, is free for up to 3TB and has ZFS/snapshots/etc, or you could deploy a Linux machine with BTRFS, etc.
DRBD does not require resizing partitions. The meta-data can be kept on a small partition on an entirely different disk if you so choose. At 128MB each, with minimal data being written, you could well plug-in a small USB Flash drive, and put the DRBD metadata for numerous partitions on it, without touching any of the hard drives.
Then, on the secondary DRBD system, you just "connect" the relevant partitions when a snapshot is desired, all changes get synced up to date, and then disconnect whenever you like. It's better than a snapshot, since it's on a physically separate system. If you had a large enough hard drive array (2TB SATA drives are cheap), you could even have a single server being the "DRBD secondary" server for dozens of other servers, receiving "snapshots" periodically, and perhaps, automatically...
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
LVM snapshots suck because you can't store the snapshot data on the filesystem you're snapshotting. Sure, there's tons of ways to come up with extra space to store the snapshot data in, but they're all gigantic pains in the ass.
All it needs is the ability to exclude particular blocks from the snapshot, which should be a ridiculously easy option to implement for anyone who's worked on the snapshot code, and then people who aren't experts in kernel hacking can take care of the rest of the layers to make it a user-friendly operation, but nobody will do that because of hurf durfy crap that doesn't account for how people actually use computers.
<xml><I><am><so><damn>Web 2.0</damn></so></am></I></xml>
I newer understod why InnoDB should allow filesystem snapshots. Is this documented anywore or is it just one of "It ought to work"?.
I mean InnoDB does NOT support a normal filesystem copy of the 3 database files as a way to make a backup.
Depending on how long you're keeping them around, LVM Snapshots are likely to be a bad choice anyway. Their intended use-case is to have a very short lifespan, because they're intended to be used like so:
1. Create snapshot
2. Mount snapshot & copy data to backup server
3. Unmount & destroy snapshot
The point behind them is to create an unchanging version of a live partition so that you can copy the data out without worrying about whether it is being updated while you copy. Since the snapshots keep a diff of all changes to the original volume, they continue to grow in size as you make changes to the original volume. When the snapshot runs out of space, it simply dies (completely... can't mount it or anything, just have to destroy it).
There are some other possibly valid use-cases (e.g., if you have simple throw-away virtual test machines, you can build a gold image, and snapshot it and then mount & use the snapshot, which allows for a quick restore to the gold state), but keeping iterative backup copies on the local volume for quick restoration isn't really the best idea.
And they only work fine if you have no qualm with seriously degrading performance over time. Windows VSS provided snapshots, called "shadow copies" or whatever, more closely resemble ZFS snapshots than say, dumb SAN or LVM snapshots where the snapshots reside in a dedicated "snapshot area". NTFS, ZFS, have filesystem level snapshots and so the FS is able to put old and stale data relatively close together, and defrags can intelligently move stale data out of the way, making a contiguous area of disk a contiguous area of current data.
If you don't believe me, run Windows with hundreds of shadow copies on a disk, say, running PostgreSQL. Write a quick script to take a snapshot every minute and keep running PostgreSQL. Defrag after one hour, and then re-run the benchmark. Defrag, run benchmark.
Then run your favorite Linux distro with 100+ configured LVM snapshots, again, once a minute during a PostgreSQL benchmark of your choice. Defrag or do whatever you think will aid the benchmark except destroying the snapshots, and re-run the benchmark.
You will then sit patiently and wait for BTRFS or something else to save the day.
Quoth Wikipedia:
4 January 2001 - Linux 2.4.0 was released (3,377,902 lines of code).
That's about the same as running Windows 2000 Server in a production environment.
And ... why would you do this? Take a snapshot, back it up somewhere, and then delete it.
*sigh* noobs...
$ man tar
+1.
u r doing it rong.
If you need to keep around such old software, it needs to be running inside Xen/VirtualBox and/or become NFS-booted so that it's insulated from the hardware. That way, you're not forced to keep around old hardware to run your old software. If you insulate with Xen/VBox at the block level you can use LVM2 on the host system to do snapshots but are still constrained by the legacy filesystem. If you NFS-boot, you can use future filesystem-level snapshottable Linux filesystems to do snapshots, or you could buy a NetApp and use proprietary software to do the snapshots, or Solaris (if it sticks around), or any of a variety of things. You can argue about which level of storage insulation is best in the long run: the filesystem level has certain advantages at least with ZFS and probably with whatever future Linux snapshotting filesystem comes along becuase of variable block size: small files get blocks in 512-byte increments, and any file larger than 128kB gets a multiple-of-128kB sized block. Since blocks are the unit of compression and deduplication, you want the largest size block possible, but not too large or you suffer from the read-modify-write RAID5-like tax. A larger block will compress better and takes only one entry in the deduplication hash table. If you insulate at the block layer then all blocks will have to be the same size and a relatively small size, which makes compression and dedup work not nearly as well because they can't give big blocks to big files. however for old software you may want to change as little as possible, and especially with sketchy linux 2.4 NFS clients maybe it's not safe to run certain apps over an NFS root, or maybe your ancient distribution doesn't support NFS booting well.
One way or another, though, you need to find a way to keep the apps running while minimizing the blocks of ancient code on which you're still dependent, and this should be your overriding concern. You need to structure your plans to encapsulate the code subject to bit-rot rather than flailing around on /. for some freshmeat app-of-the-day that claims to solve * with FUSE and some stupid Perl script. This is the difference between a serious professional douchebag who surveys the industry and can smell the difference between high and low quality, and a pathetic flailing do-my-homework-for-me everything-inclding-windows-has-stengths-and-weaknesses-right-tool-for-the-job doomed blinking medicated idiot douchebag. Do not be that douchebag.
Easy on the language...
But LVM is *the* solution on Linux. It's not very difficult to set up, and is very stable. As an additional bonus it supports all file system types (as long as they can exist on LVM volumes).
The 2.4 series was the last stable series of linux kernels in existence. 2.6 is in a perpetual state of bleeding edge, which makes it a gable to use on a system you care about. It is one of the reasons people (like myself) switched from 2.4 to one of the BSD's.
Configurations
Data
OS
/root) System. System Configs: This is /etc/ and key entries in /var for the most part.
/etc/ a copy of key data, and either a kickstart file, dpkg list or other tool (Like a wiki plan) to re-build the box.
Configurations: Two types Users Configs: this is kept in their home so no need to worry aboutthat as normal backup takes care of it (exception can be
Data: By in large this is also maintained in homes, for that too backup software is the key. Data could also include software that either you made the mistake of building locally without some kind of packaging to repeat, or, that is 3rd party. Scripts and Cron Jobs also fall into this realm along with logs.
OS: That's why they make CD's. You just install. To make sure you get all of the same software, both rpm based, and deb based systems have ways of taking an inventory and replicating the inventory to another box.
There is no concept of registry in a Linux box. (unless you run some of the newer gnomes but that registery is by user so it's in the home.) This means you don't have to have restoreable clones to re-create the box. It's sufficient to have a copy of
On the cheap tar and gzip are all the tools needed. More involved. Puppet
I'm sorry, I'm to tired to be witty at the moment so this message will have to do.
SVC or CVS?
Actually, he is asking for a CVS like feature. He's basically saying, I can do this with that, how do I do it here without rebuilding the server or taking it off line. In effect, he is asking for what he doesn't know about to make the thing work like he wants.
He's basically stating that some things could work but won't work because he either has too old of a system, or the wrong file system, or they aren't using the volume manager and changes in that regard are too much. So know he wants to know what's left that could achieve this goal.
I tried figuring out how to do something like this a couple months ago: got something going with BTRFS. http://unquietwiki.blogspot.com/2010/03/quick-local-backup-with-rsync-btrfs.html
Life is irony, and nothing ever goes as planned.
Win2k is still used widely all over the world in production environments.
The problem with systems that work is that you're usually not to touch them until they stop working :(
Ext3 on LVM2
Seriously, that's all you need. Why overcomplicate things?
btrfs will have this in a few years... when it's reliable.
ZFS has it now if you choose to run OpenSolaris or FreeBSD.
Explain why not wanting to reserve space for snapshots is using a computer improperly, because that's a pretty major claim given that nearly every filesystem that supports snapshots doesn't require reserving space for them at filesystem creation time, and a number of block-level systems support it as well.
I can't parse your first question. Your second question makes no sense either. I don't want to reserve space inside the partition, I want to use space in the filesystem.
It's dumb, there's no reason for it other than a dogmatic clinging to some "right" way to do things. Not every system that needs to be snapshotted is a server with years of usage history and hot-swappable disks owned by a company that can afford to oversize their disks by 50% or more.
<xml><I><am><so><damn>Web 2.0</damn></so></am></I></xml>
Even if you are using SUSE or RHEL, support for 2.4 is about to vanish completely. The last version of RHEL to use a 2.4 kernel was RHEL3 - which goes EOL October this year. I actually have one very old system to convert because of this. There is no version of SUSE using a 2.4 kernel and still in general or extended support. Even for 'self-support' (it's a bit of an oxymoron - it just means you can use the forums and the knowledge base but nothing is going to get fixed by Novell. How this is different from 'Googling it' isn't obvious to me), the last SUSE support for 2.4 will EOL in November 2012.
You are seriously missing out on Solaris, then. ZFS is the bomb, zones are so much better than anything Linux has to day (including OpenVZ).
Plus it supports all the applications Linux does. Whoohoo!
Check out rsnapshot, which uses rsync and hard links.
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
And ... why would you do this?
To speed up and simplify restores.
The vast majority of "need a backup" situations are end users accidentally deleting things. This means a simple self-service restore capability that keeps, say, 1-2 weeks worth of hourly snapshots, will cover 80%-90% of restorations in a very short period of time with nearly no administrative overhead.
You can't do this with LVM (well, you can try, but performance is going to be dismal and it's going to be a nightmare to configure and manage).
The choice isn't that simple. LVM comes with its own complications, including a tendency to get volume offsets "wrong" so the file system data doesn't align nicely to RAID stripes. This is not good for performance.
This is only going to happen if your partition is misaligned, in which case whether or not you're using LVM is irrelevant.
The solution is to either a) use whole-disk PVs (preferable), or b) create properly aligned partitions.
Also, LVM has only recently acquired barrier support, and the combination of no barriers + write cache can be quite dangerous if power is lost. Even battery backed cache won't save you if you use a journalling file system (and everybody does these days) because request ordering isn't guaranteed.
Again, nothing to do with LVM, such a failure will affect any system.
Not even a LMGTFY link? Your sarcasm is wholly inadequate :-)
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The way those filesystems do it is that they implement an allocator of resources beneath the actual "filesystem", so that you can snapshot things by marking blocks CoW and then allocating non-filesystem space for the metadata.
As it happens, ext and friends don't roll that way, so adding that functionality breaks compatibility with those filesystems.
Also, most of the new filesystems which allow snapshots in the way I describe have some awesome problems - like needing to truncate a file in order to rm when the filesystem is full, because the way the allocator structure works means that you can't know ahead of time how much space it takes to atomically delete a file, either...
It's only an insult if it's not true.
The whole point of VSS and similar snapshotting services is to reliably make consistent snapshots of live systems - you don't want downtime for your production servers!
Maybe rbackup would be useful? You can retrieve individual files, and data transfer/storage are reduced so you can back up more often.
I'm not reading all of this crap, but there are plenty of methods for storing/restoring data that DON'T involve making backups. Here's a few:
Use dar (search for "dar disk archive" so you don't get daughters of the american revolution)
- dar allows you to get many of the features that snapshots provide by simply backing up files to disk. It supports incremental backups, and supports deleting files on a backups so when you restore from a dar backup it really does restore a given directory to it's state when the backup was made. It's also extremely complex, so you will probably end up writing scripts to automate using it.
Other Options:
-You can also use tar, but it's not as versatile, and only sort-of supports incremental backups, you could probably hack around this by scripting the capabilities yourself, but it's much simpler to use dar instead.
-Use dump/restore (I haven't done this, and this method of backing up is OLD so there may be limitations that make it unusable in this context)
-Use dd to clone partitions/disks to image files, takes a long time and creates huge files, requires harddisks with identical geometry for a restore. (well, not quite, but it makes it alot easier)
There's also some client/server stuff like bacula and amanda, but I don't use them, it seems like much more work than is neccessary. Personally I just do dar backups to an external harddrive (or nfs-mounted share)
You want to take the server out of service overnight? Because if you try that trick on a live running filesystem, you are asking for corruption on the output side. And no, I don't know an alternative in this case.
suso-- reread it with the assumption he isnt an idiot, you're making an implicit assumption about how he has his servers partitioned.
ok for most of what needs to be done Rsnapshot is awesome.
Rsnapshot uses rsync and some creative hardlinking to make a pretty nice snapshot. I find that it is awesome, until you need to transfer the archives to a new machine. It is packaged, so it installs nicely. If you have live databases you have to get trickier,, one simple way is breaking a raid 1 mirror, and running rsnapshot on the old drive.
just kidding.. the rebuild would jack your system up. And that assumes that you have the machines in raid. For live data that needs atomic control rsnapshot is really the wrong tool.
Storm
The primary reason for keeping a snapshot online is to avoid the delay in having to go back to tape for a single file some moron deleted.
Otherwise, yes, older snapshots should eventually be deleted, just like tape cycling.
Heh. I still have both in production -- I sometimes wish I didn't, but the feeling passes when I think about how much mess it is to replace them.
(In fact, I still have an NT 4.0 machine and a linux machine with a 2.3 kernel on it; 'tho I'm surprised their hard drives still work -- SCSI for the win.)
LVM snapshots also just aren't all that good.
They require you to pre-allocate space, so you have to guess how much copy-on-write difference will accumulate between the original and snapshot over the lifetime of the snapshot.
If the snapshot runs out of space, it *should* cleanly disable its self. Pity about the file system mounted from it that has no idea its backing block device just vanished. It gets messy, fast, when an LVM snapshot runs out of storage.
LVM snapshots are really inefficient, because they track all block changes, not just user-level file data and metadata. This massively bloats the snapshot, reducing how long it lives until it runs out of backing store and disables its self.
LVM snapshots don't share backing store. If you have three of them, snapshot t+3 has to store all the data snapshot t+2 and snapshot t+1 do, and so on. The differences between the real fs (t) and snapshot t+1 land up being stored three times in three separately allocated backing stores. You waste a HUGE amount of space this way, and it's hard to reliably predict how much you need so your snapshots often vanish out from under you are you're trying to use them.
LVM is useful, but for someone used to the Volume Snapshot Service (VSS) on Windows servers, to ZFS, or to any of the "enterprise-y" file systems often seen deployed with big SANs, it's just going to make them cry.
Exactly, about 2 1/2 years ago I worked for a large company that everyone here has heard of that at the time was running ~4000 servers on a modified Redhat 6.2 image. There was a large code base that got lost sometime in the start-up phase of the mid 90s that was much easier to never touch the OS then to re-write the code.
Paying taxes to buy civilization is like paying a hooker to buy love.
Go lookup dynamic vs basic volumes and quit being a prick.
It's not that simple.
Maybe your budget is zero, but backups in a work environment should be important.
OK a SAN costs money, but it will work with your ancient 2.4 kernels. Snapshot with ease and power. Add a few terabytes without powering off your systems. Plus you can do a lot of things like synchronous replication (for more $$$) and/or clustering. Virtualization is orthogonal, doing both might be a very good idea since you might manage not to change anything at all in the production systems.
I love it when all the supported filesystems also work as well
It's already been mention, but I'd be looking at snapshots in the array and/or, if your pockets are deep enough, VxFS. Host overheads drop when you're snapshotting in the array (assuming COFW isn't too onerous.) Once you're in the array though, you're operating at the block level (i.e. below any application or filesystem.) Your challenge here is to ensure your snapshots contain useful data and not an arbitrary bunch of 1s and 0s. If you're dealing with file server data, normal snapshots are generally fine. If you're running an app (e.g. Oracle,) then you must quiesce the app before taking a snapshot. If you don't, then your snapshot will be crash consistent. If you quiesce the app, your snapshot will be application consistent. There is a world of difference between the two.
Given that the OP apparently has no interest in changing his filesystems, it seems to me that the obvious solution is a neat little rsync script run as a cron job. Why complicate life?
If you use --link-dest=DIR, rsync will hard link to any files that are identical, so you can have snapshots that are accessible as an entire tree but that consume little more space that a snapshot delta.
what about duplicity ? (incremental snapshots, command-line tool, librsync-based, used by "deja-dup"), rdiff-backup and rsnapshot
Some of our systems still use token ring coax networks and OpenVMS servers.
The problem is that the fuckers just work... and keep on chugging along happily in the basement of the plant...
Again, nothing to do with LVM, such a failure will affect any system.
Of course not. That's what barriers are all about -- making journalled file systems actually work. LVM silently discarding barriers is nasty. Fortunately it has been fixed; I haven't actually tried it out though.
Finally! A year of moderation! Ready for 2019?
Plus it supports all the applications Linux does. Whoohoo!
Maybe so, and I do remember my days of trying to keep various Free Software running on a variety of Unix systems with a certain fondness. However, I have no desire to relive the experience.
Finally! A year of moderation! Ready for 2019?
Assuming the current situation : I don't see a lot of benefits of backing up the OS partitions. You'd better backup any config file that requires a lot of work to restore or version them using cvs/svn repository. If you are very hectic to backup You use rsync considering its mysterious options... Recommendations : - Better migrate your systems to latest supported versions. - Better use lvm for better manageability and more flexibility... Regards,
If your'e thinking about the time when compiling a (pretty much any at all) GNU app on HPUX or AIX too like three weeks of code modifications and Makefile manipulations, then long gone are those days :)
OpenSolaris is generally not any harder than your (randomly selected) Linux distribution.
And yes, ZFS and Zones are... THE thing.
Period.
This signature is DRM protected. By the DMCA, you are not allowed to counteract or oppose to it.
The OP sounds like a coded attempt to slander one OS because he's using the wrong tool on an install that will not support it while claiming it can be done on the other OS (assuming that you use the right tool on an install that will support it.)
Isn't that really the double standard you are referring to?
If it ain't broken, don't fix it.
What a depressingly stupid machine.
>Not everyone runs Ubuntu.
But Fedora, Mandriva, PClinux, SUSE, etc., even Slackware all distribute 2.6 kernels now and have for some time. The fact that support for 2.4 is in it's last throes doesn't appear to be a reason to actively resist upgrading.
need updated
Are you from Central Ohio? My wife is a linguist at OSU, and the "needs <verb>ed" construction is a frequent subject of conversation (among linguists here), since it is really only native to a very small area.
SIGSEGV caught, terminating
wait... not that kind of sig.
He's probably not even allowed to install security updates without filling out three change request forms and waiting a month for final approval.
Damping absorbs vibrations. Dampening is caused by moisture.
VM is the closest thing to what you want to do in practice. Create a virtual server. Snapshot it using the VM tools. End of story.
It is a perfect timing to be asking this question. CTERA has just announced Next3 this week (http://lwn.net/Articles/391339/) and Next3 is available (for kernel 2.6). Next3 was designed for this exact purpose: providing Volume Shadow Copies over Ext3. Next3 snapshots are instantaneous and have small performance overhead. With CTERA NAS appliances, Windows clients can actually use the "Previous versions" button to view file history, just as easy as with a Windows file server. Next3 does not try to compete with Btrfs (or ZFS), it is but a complementary feature for Ext3, which people do seem to find missing and will hopefully be merged also into Ext4 some day.
Back in the day one of my employers ran a FileMaker server for all of their databases. The FileMaker server would crash fairly often and when it was reloaded it would perform a consistency check on each database. The consitency check would process every record entry in each database to see if it was closed properly. They had multiple databases with millions of records, so it could take days before the checks would complete and the databases are brought back online.
The solution was to have multiple snapshots. If the server crashed, we'd restore the databases from the most recent snapshot. We'd lose some data (whatever was added between the snapshot and the crash), but it was worth it to avoid the lengthy downtime from the consistency checks.
The clash of honour calls, to stand when others fall.
Unfortunately EXT type of file systems do not support this as others have posted about there are many other ways to do back ups. You might want to look at BTFS it is still experiential at this time but it have many cool features built in that I think you are looking for http://en.wikipedia.org/wiki/Btrfs
Circa 1980 or so. It's depressing really, how far behind most people are. The really depressing thing is they continually insist they have a clue what they're doing and others have to do it their way too. Then they have an epiphany and re-invent the wheel, all over again, but this time in Ruby (with added expressivity) so it's not really the same thing at all.
Deleted
Seriously. Problem solved. You could even shock horror, do it properly and take the backups offsite in case someone spills his Mountain Dew on the "mission critical" servers under his desk.
No, wait. It's much better to spend your time re-inventing backups. Go ahead.
Deleted
I am. I grew up south of Sandusky, live in Columbus now.
To be honest, I don't see any problem with it, but I claim no expertise in English. I guess the "proper" method would be "need(s) to be"? We just shortened it. ;)
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
2.4 is too old? I'm working on re-setting up a system for my dad's florist shop for the "recipe" for each floral arrangement. The thing runs Red Hat 7--kernel 2.2.
The program is written in COBOL, for crying out loud! I tried installing Ubuntu Lucid and chrooting to the Red Hat partition, but that ultimately failed, so now I have to try installing Red Hat 7 and see if it works better that way.
Running ext3 on raw partitions really gives you no latitude for snapshots... but why do you need them?
The conventional wisdom for snapshotting is to create a consistent point in time view of an FS. This is something thats often needed for things like db's. for example, if your running a db, you want all your db files snapshotted at the same point in time (ignoring logging for now) simply for consistency. This is where the rsync ideas fall on their bum, because rsync just wont happen fast enough to create a consistent point in time across the entire database and you end up with a corrupt db. As has been pointed out though, snapshots are NOT necessarily safe ways of backing up database data, the database should be aware of what your trying to do (see hot backup) and most can be made to do just that.
But then again, if you can rsync, you can backup (and typically thats a better idea anyways) - i.e. see bacula, etc. Rsync has its uses, but a backup tool it often is not.
There is one caveat, if you running on a SAN then there is no SAN (that i know of) that doesn't do snap-shotting in this day and age (though, in some cases it comes at a $ cost). Even just about every iscsi san does it.
Your only other option is to be migrating into LVM (see caveat below). IMHO, this is the best idea cause lvm doesnt just give you snap-shotting, it gives you much more besides in terms of flexibility.
Option 3 (and this ones a tough one) is to migrate into DRBD (or LVM is going to support dm-replication soon). But, you can migrate to DRBD now without too much effort (even in 2.4 iirc), and this would allow you to replicate ext3 data to another host running lvm where you CAN snapshot. But, as i said before i think your best choice is to migrate into lvm (drbd will cost you more in terms of sheer volume of work and drbd is not fun at the best of times).
The solution was to have multiple snapshots.
Argh!!!!!!
The solution is to use a s/w-h/w combo that doesn't crash on a regular basis.
"I don't know, therefore Aliens" Wafflebox1
"nearly every filesystem that supports snapshots doesn't require reserving space for them at filesystem creation time"
I don't think the guy wants to switch filesystems: "but I need something I can use on my existing ext3 file systems"
If everyone just googled everything, there would be no ask slashdot.
You might note that I commented on the format of his response, not on the content. He already referenced Google before I came along. Ergo, while I do not comment on the validity of your statement, it would be more on-topic if posted as a reply to the grandparent's post.
Unity? Screw that: XFCE. Slashdot Beta? Screw that: SoylentNews. Australis? Screw that: Pale Moon. UX developers DIAF
Oh there is certainly nothing wrong with it. It is a dialect feature that exists. It is interesting principally because it is so extremely localized (unlike, for instance, my own native "might should"), and more specifically localized to the area surrounding the university at which said interest occurs.
You should see my wife's students, though, when she writes "The car needs washed." on the board, and then asks those who feel that such a sentence is natural to raise their hands. Half the class does almost every quarter, and then each half looks at the other half like they've got their heads on backwards. People who don't have the construction think it sounds really really odd, and people who do have it think that everyone else is crazy for thinking it odd.
SIGSEGV caught, terminating
wait... not that kind of sig.
This is exactly the point. 2.6 is bleeding edge, it is not for production servers. You don't get it if you run something as critical as a router on Linux. Juniper chose BSD for JuneOS for a reason.
First of all, it's JunOS, not JuneOS. Second of all, companies like F5 (also very reputable) switched from BSD *to* Linux. Cisco's highend shit runs on QNX for that matter.
However in the case of *all* of these platforms, they're all just being used for management, all of the switching and routing is done by ASICs...
Ogre Wedding Planners llc.