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NetBSD's Real-Time Network Backup

Posted by ryuzaki0 on from the old-hardware-power dept.

jschauma writes "One of NetBSD's developers, der Mouse, was interviewed by DaemonNews about his real-time network backup system (originally presented at BSDCan 2005), where changes to your local filesystem are automatically propagated to a backup server. In his interview der Mouse tells about his idea, how it works, and of course, how cool it is."

11 of 166 comments (clear)

  1. Cool, but not new by BlankStare · · Score: 2, Informative

    This concept has been in play for years as a commercial product for Disaster Recovery, Veritas Volume Replicator (VVR).

  2. Re:Der Mouse? by Red+Flayer · · Score: 2, Informative

    "Those crazy Germans."

    No, that would be "der Maus"

    You crazy Americans -- Hier ist der Maus!

    --
    "Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
  3. Re:Der Mouse? by isecore · · Score: 2, Informative

    Those crazy Germans.

    According to the article, he's canadian.

    --
    I enjoy large posteriors and I cannot prevaricate.
  4. NBD? by mikeee · · Score: 3, Informative

    How does this compare with Linux Network Block Device? Sounds very similar.

    There are pretty mature commercial tools for this stuff, as well - Veritas' VVR replication comes to mind.

    1. Re:NBD? by SmallSpot · · Score: 2, Informative

      Not the same as NBD, but it is very similar to DRBD (http://www.drbd.org/). I've used DRBD before, and it works quite nicely.

  5. Re:How is this different from Windows VSS? by Anonymous+Struct · · Score: 3, Informative

    As of Windows 2003 R2, there is a capability to do a VSS type of thing over the network to a remote server.

    I'm a little ashamed that I know that, but it's true.

  6. DragonFlyBSD has the better way... by KonoWatakushi · · Score: 2, Informative
    There is actually a better way, and it is being implemented in DragonFlyBSD. Instead of duplicating writes at the device level, VFS operations are logged to a journal descriptor, which may be a file or network pipe. As this is performed in a VFS layer, it is possible to use with any filesystem. However, it is not limited to remotely (or locally) mirroring a filesystem; with the journal available, it will also be possible to rewind the state of the filesystem to any point in time, subject to the journal size.

    So what you have is not only a real-time backup, but also the ability to unwind any possibly damage after a break-in or other event. If your backup server is only running a journalling client, it can be made extremely secure, and also provide an excellent auditing tool.

    It would also be possible to delay the streams and have arbitrarily old filesystems available. Or to use a local journal as a buffer to smooth out the IO load as it is piped off site. It could also be used to augment a non-journalling filesystem, for crash recovery purposes, assuming your filesystem provides at least some consistency guarantees. In fact Netapp does something similar by logging FS operations to NVRAM, while the filesystem only writes consistentcy points periodically.

    Although I haven't read about the NetBSD work, I am sceptical that they could get the error handling to work correctly at that level. With the DragonFly journalling, there is support for transactional consistency, as well as recovering from interrupted network connections. While it is not complete, much of it is in place and functional.

    See the mountctl manual page for attaching a journal to a mount, and the jscan manual page for processing the journal.

  7. Re:B.S. D? by mattyrobinson69 · · Score: 2, Informative

    In linux a RAID array can contain any block devices, including network block devices, ramdisks, whatever.

    (I read this in a linux software RAID tutorial once)

  8. Network Appliance by SignalX · · Score: 2, Informative

    NetApp has been doing somthing similar for a very long time. A lot of people use the Sun boxes on the frontend to boot or attach to the storage appliance and let it do the backups. It saves space and saves the server from having to do it.

  9. Re:Good idea, but there has to be a better way by ivoras · · Score: 2, Informative

    Sadly, no, not even to DragonflyBSD. Don't know why, but maybe it's because it uses kernel threads internally...

    --
    -- Sig down
  10. Silly OBSD Troll (Re:... mock Theo.) by kjs3 · · Score: 2, Informative

    Actually, he's been around as Der Mouse since I was in college (circa 1985). I ran the xterm replacement he wrote back then. Long, long before Theo had his hissy fit and forked off OBSD. Of course, a trivial Google would have shown that, but hey, an AC would want to miss out on an ad homen flame...