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Fedora 11 To Default To the Ext4 File System
ffs writes "The next release of Fedora, 11, will default to the ext4 file system unless serious regressions are seen, as reported by heise online. The LWN story has a few comments extolling the virtues of the file system. Some benchmarks have shown ext4 to be much faster than the current default ext3. Some of the new features that matter for desktop users are a faster file system check, extents support (for efficiently storing large files and reducing fragmentation), multiblock allocation (faster writes), delayed block allocation, journal checksumming (saving against power / hardware failures), and others. The KernelNewbies page has more information on each feature. As is the extfs tradition, mounting a current ext3 filesystem as ext4 will work seamlessly; however, most new features will not be available with the same on-disk format, meaning a fresh format with ext4 or converting the disk layout to ext4 will offer the best experience."
Ext4 is not a SAN or distributed filesystem. GPFS/lustre/GFS remain a good choice for that.
So where can I see some benchmarks showing just how much of a slowdown I can expect after switching from ext2 to ext4? All the benchmarks I see around here compare it to ext3 and to ReiserFS only. Also, is it possible to run ext4 without the journal? Any benchmarks on that? (Oh, and please, don't bother with the reliability lectures. I couldn't care less.)
I still haven't seen sensible benchmarks for ext4 with respect to how large directories scale, interleaved small file read and create, and small-file write with one fsync() at the very end (the only real world case.)
At this point, I have to wonder if the emporer has no clothes, or if the people posting benchmarks are just idiots.
Some of the minor features are just... less than desirable.
for when you need to partition your wife.
I do not propose offering migration from ext3 by default, at this point, due to bugs in that process, and extra risk involved. Perhaps an "ext4migrate" boot option could be used to expose it for further testing.
ReiserFS isn't actively maintained. In addition to that ext3 and now ext4 have learned quite a few new tricks since ReiserFS first appeared, you can now online resize an ext3 filesystem, it supports hashed b-trees, which should speed up directory handling, it is getting an online defrag tool and a bunch of other goodies. So many of the benefits that ReiserFS originally brought to the table can now be have with ext3 or ext4.
Clustered file systems and local file systems are of necessity different. Most of what makes a clustered FS useful would be pure dead weight on a local FS.
What I would like to see are clustered FSs which are easier to set up. I.e. You go to the 1st machine and start up the cluster config program and it asks: "Is this the 1st machine in your cluster?" Once you say yes there, you go to the other machines in turn, fire up the same program and say no to that question and enter the IP of the 1st machine.
Once all those machines are added, the next step is to select. "Add Local disk to cluster pool" and then you select partitions on your local hard drive that should be in the pool. They don't have to all be the same size either.
Once you have done that for each machine (either by going from one to the next or using the the tool on the primary node to add disks from each one (or a whole group of them if they are already partitioned in the same way).
Then you just start mounting this virtual disk and dumping files to it.
The technology exists to do this. The problem is that each time it's done' its a manual process tantamount to a programing job. Who want's to take up the task of tying all the pieces together to make the setup feel this simple for the user.
Additional functionality (like tuning the FS for Database or Email usage and failover hierarchy) would be added over time and in a way that dose not detract from the simplicity of that basic setup.
--= Isn't it surprising how badly I spell ?
I'm glad to see Red Hat and Fedora taking the hard steps to push our technology forward. Precious few organizations employ people to work on things like this, instead expecting others to do the hard work to create and integrate disruptive core technologys. I know Red Hat employs people to work full time on ext4 and they have a person working full time on btrfs (which by all early accounts is supposed to be revolutionary and kick the crap out of everything else out there [even the fabled ZFS] (it pains me to say thanks to oracle for btrfs, but one of their employees is the primary driver) Someone has to do the hard work of being a leader, putting in engineering time, and fixing the bugs before the fanboys can consume (and all too often get credit for) new technology. Thank you Fedora for both the freedom and the constant drive to be on the leading edge of technology.
It's already a technology preview in RHEL 5.3.
As is the extfs tradition, mounting a current ext3 filesystem as ext4 will work seamlessly;
Shouldn't that be the other way around? If you mount an ext4 filesystem as ext3 the system will work, using only the ext3 subset of ext4. However, if you mount an ext3 as ext4 the system will try to use ext4 data structures which are simply not on the disk.
... or am I missing something?
When our name is on the back of your car, we're behind you all the way!
Yes you are missing something. :) The superblock on all extX say what features they support. So when you mount ext3 as ext4 the mount code can look what features that FS supports and use what new features it has available that won't break it as ext3.
If you mount and ext3 fs as ext4 you'll get all of the benefits of ext4 like the enhanced inode allocator and what not, but you won't get extents so your huge file support is limited just like ext3)
An ext4 fs can NOT be mounted as ext3 as the files will be stored using new features (like extents) which ext3 doesn't understand.
Make sense? There will be (or is?) a conversion tool which will be able to downgrade ext4, but you can't just mount backwards.
^I'm less concerned about what the guy did who spearheaded its design, and more about it becoming abandonware.
Sounds like someone should learn perl or python and get to it!
c++;
In fact suse changed their defaults from reiser to ext3 long time ago. The main reasons were: scalability on SMP, xattrs performance, lack of mainteinance, lack of a upgrade path...
People are looking forward to ext4 because ext3 has performed so poorly compared to ReiserFS. No one wants to touch ReiserFS, regardless of its performance advantages over anything out today, because Hans was a psycho.
In a previous job, we tried everything we could to use ext3 for one of our server-based products, but the performance was never good enough compared to ReiserFS v3.
Hopefully the ext4 folks have learned how to implement all the excellent ideas Hans Reiser came up with between ReiserFS v3 and ReiserFS v4.
Not to mention ext3 doesn't lose random OS files in the wake of a sudden power failure like reiserfs does. I might be alone on this event but after it happening on 3 different systems at 3 different times I'd think it would be documented more. I've always thought reiserfs was overrated and even if there is a speed increase data integrity is a lot more important to me.
It doesn't bother me that the creator is a convicted murderer, it does bother me that the file system gets away with murder all the time.
"Some things have to be believed to be seen." - Ralph Hodgson
We all have our talents.
I have bartered PC repair and System admin services for competent legal advise, accounting service and even medical care on one occasion (Every desktop in my dentist's office had the "worm of the month").
Sensible people do what they are good at and wherever possible get others to do the other things.
This little project may take a day or a few months for a pearl wizard. I'm not sure. I do know it would take me years, if it got done at all.
--= Isn't it surprising how badly I spell ?
Red Hat ship some web based tools called Luci and Ricci which basically do all of this, with a pointy-clicky interface.
Rich.
libguestfs - tools for accessing and modifying virtual machine disk images
I have used them.
1. The work for sharing a SAN but are not so useful for clustering local disks.
2. Even doing what they are good at, setup is a bit more tedious than I would like.
BTW: A nice setup menu dose not need to be GUI. Many of the console tools in the system-config-whatever series are nice.
--= Isn't it surprising how badly I spell ?
Apparently there is a serious risk of data loss at this time in case of power loss (at least in ubuntu). http://ubuntuforums.org/showthread.php?t=1040199
Do you not know what Fedora is? Fedora is a bleeding edge distro. One that is openly acknowledged by Red Hat as being their Beta testers for new technologies that might eventually make it into RHEL. So this is just a standard thing Fedora does.
One of my biggest beefs with ext3 in the data center is the required fsck periodically. Redhat won't support jfs or xfs (which I can get from CentOs) but some vendors won't support anything that isn't on their supported platform list (IBM Clearcase for one).
So is ext4 going to force a fsck at boot, which takes 1/2 a day with ext3 on some of my multi-Tb systems? Will Redhat finally adopt a better server filesystem? These are the questions that some of us doing professional Redhat support are asking.
Overrated, Troll, and Flamebait mod points are not to be used towards posts you disagree with. That IS censorship.
"Why not just use ReiserFS?"
Vendor lock-in?
Ext4 is orders of magnitude faster than Ext3 regarding fsck time. Your half-day checks will almost certainly be reduced to minutes. The developers rewrote the algorithm to not require as intensive of a search in phase 1.
If it's really important to get the machines up in minimal time (even at risk of some data loss) then you can turn off the auto checks entirely.
Actually, ext4 can be mounted as ext3 provided extents are disabled when creating the ext4 fs. This may be useful for someone who wants some of the new features of ext4 but needs to mount the media on a machine that can't be upgraded to support it.
I am becoming gerund, destroyer of verbs.