On Wed, Sep 02, 2009 at 10:14:05AM -0500, Les Mikesell wrote: > Pieter Wuille wrote: > > In our case, the BackupPC pool is stored on an XFS filesystem on an LVM > > volume, allowing a xfsfreeze/sync/snapshot/xfsunfreeze, and using > > devfiles.pl on the snapshot. Instead of xfsfreeze+unfreeze, a backuppc > > stop/umount + mount/backuppc start is also possible. If no system for making > > snapshots is available, you would need to suspend backuppc during the whole > > synchronisation. > > In fact, the BackupPC volume is already encrypted on our backup server > > itself, allowing very cheap encrypted offsite backups (simply not sending > > the keyfile to the remote side is enough...) > > > > The result: offsite backups of our 400GiB pool, containing 350GiB data, of > > which about 2GiB changes daily, is synchronised 5 times a week with offsite > > backup in 12-15 hours, requiring nearly no bandwidth. This seems mostly > > limited by the slow disk I/O on the receiver side (25MiB/s). > > > > Hope you find this interesting/useful, > > The one thing that would bother me about this approach is that you would > have a fairly long window of time while the remote filesystem chunks are > being updated. While rsync normally creates a copy of an individual > file and does not delete the original until the copy is complete, a > mis-matched set of filesystem chunks would likely not be usable. Since > disasters always happen at the worst possible time, I'd want to be sure > you could recover from losing the primary filesystem (site?) in the > middle of a remote copy. This might be done by keeping a 2nd copy of > the files at the remote location, keeping them on an LVM with a snapshot > taken before each update, or perhaps catting them together onto a > removable device for fast access after the chunks update.
You're very right, and i thought about it too. Instead of using a RAID1 on the offsite backup, there are two separate backups on the offsite machine, and synchronisation switches between them. This also enables the use of rsync's --inplace option. Keeping an LVM snapshot is a possibility, but it becomes somewhat complex to manage: you get a snapshot of a volume containing a filesystem whose files correspond to parts of a snapshot of a volume containing an (encrypted) filesystem containing a directory that corresponds to a pool of backups... Catting the part files together to a device after transmission isn't a complete solution: what if the machine crashes during the catting...? -- Pieter ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/