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Linux Backups Made Easy

Posted by michael on from the no-more-tapes dept.

mfago writes "A colleague of mine has written a great tutorial on how to use rsync to create automatic "snapshot-style" backups. Nothing is required except for a simple script, although it is thus not necessarily suitable for data-center applications. Please try to be gentle on his server: it is the $80 computer that he mentions in the tutorial. Perhaps try the Google cache." An excellent article answering a frequently asked question.

7 of 243 comments (clear)

  1. 'man dump' by isa-kuruption · · Score: 2, Interesting

    What's wrong with dump? It works great, and you can send stuff to gzip, bzip2, etc for data compression... even pipe the stuff over ssh to a server somewhere else. Dump also supports incremental backups. It also works on a lower level than rsync (which works on the filesystem level) and supports multiple volumes easily.

  2. Re:thank you... by zrodney · · Score: 2, Interesting

    Google cache

    yes -- that was a refreshing change from the
    usual postings where the page is /.ed . thank you!

  3. oh my, rsync backups roxxor by Dr.+Awktagon · · Score: 3, Interesting

    I've been doing backups this way on Linux for aLongTime(tm). On FreeBSD I've also used dump/restore to an NFS-mounted RAID drive (does dump work okay on Linux these days? I've always been afraid to try it for some reason, maybe earlier versions weren't stable).

    rsync is just so cool. First of all, it can work over the network through ssh, or through it's own daemon (faster), or on a local filesystem. You can "pull" backups from the server or "push" them from the client. Over the network, it can divides the files into blocks and just sends the blocks that are different. It has a fairly sophisticated way to specify files to exclude/include (for instance, exclude /home/*/.blah/* can be used to not save the contents of everybody's .blah directory, but keep the directory itself). You can set up a script to just backup given subdirectories so you can checkpoint your important project without backing up the whole show. etc etc.

    I use it both to save over the network using the rsync daemon, and to a local separate drive. On a local drive it's great, because you can easily retrieve files that you've accidentally deleted, just using cp. It's also great for stuff like "diff -r /etc /backups/etc" to see if something changed.

    I never thought of his technique for incremental backups, but since it uses hard links, I wonder how that interferes with the original hard links in your files?? Looks interesting.

    There are many flags and options that rsync has, here are the ones I use to pull complete backups from another host onto a local drive (yeah --archive is a bit redundant here).

    rsync --verbose --archive --recursive --links --hard-links \
    --perms --owner --group --devices --times --sparse \
    --delete --delete-excluded --numeric-ids --stats --partial
    --password-file=/root/.rsyncd.password \
    rsync://backupuser@xyz.dom.com/full/ \
    /backups/systems/xyz/
  4. What I'd really like... by MadAndy · · Score: 5, Interesting
    This method, like most backup solutions, doesn't take a backup as at a specific instant, but instead takes it over a period of time - the length of time required to make the backup, which can be a problem if the data being backed up is changing all the time.

    A few years ago I saw a neat (expensive!) disc array that could 'freeze' the disc image at a single point in time so that a backup could be taken from the frozen image. The backup software saw only the frozen image, while the rest of the OS saw the disc as normal including updates made after the freeze occurred. The disc array maintained the frozen image until the backup was complete, guaranteeing a true snapshot as at a specific instant in time.

    I wonder whether such a thing would be possible in software. Possibly it can even be done through cunning application of the tools that we already have. I imagined that you might be able to do something like it by extending the loopback device interface. Does anyone out there have any cunning ideas?

  5. What about backups to tape ? by Fred_A · · Score: 2, Interesting

    Backing up to your disk is all very good agains errors of manipuation, but what if the disk fails?

    And what about people like me who backup to a DLT (or whatever) tape drive? Not much use then either.

    In any case I don't see this as being extremely useful in the real world (i.e. beyond the casual backing up of a home machine)...

    --

    May contain traces of nut.
    Made from the freshest electrons.
  6. i've been slashdotted! by mikerubel · · Score: 4, Interesting
    This slashdotting comes as a bit of a surprise; many readers have sent me improved scripts that I haven't quite gotten around to posting yet. I'll try to put them up later this weekend when the slashdotting dies down.

    The site was never down; it's just that my roommate, a windows user, noticed the connection was slow and reset the cable modem. He's quite upset about being unable to play Warcraft III. :)

    I've never had a slashdot nick before, so I just created this one today. I'll try to go through some of the comments and provide useful feedback.

    Thanks for your interest everyone!

    Mike

  7. Re:The answer? by mikerubel · · Score: 2, Interesting
    I wonder how he discovered this? I can't find it in the man page.

    Rsync source code, then a lot of testing! :)

    Mike

    ps: You're right, if there is any change in the file, the original is unlinked first, then the new one is written over top of it. So it does work as advertised! Thanks for your help answering questions btw.