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On Tue, 20 Oct 2009 13:18:41 +0100 (BST) ste@xxxxxxxxxxxxxxxxx wrote: > > 2 USB drives where periodically rsync is run to duplicate drive 1 > > onto drive 2. Drive 1 is static, drive 2 (should) get removed > > every evening and taken off-site. > > > > If the two drives were setup in a software-based RAID-1 (mirror) > > configuration, would they automatically reconcile any differences > > when drive 2 was re-attached? If not, how can differences between > > two software RAID-0 drives be reconciled? Is there a command that > > initiate the reconciliation? Can this be added to a udev rule so > > that when drive 2 is re-attached the reconciliation happens > > automatically? > --snip-- > > Interesting. I guess you could do that, but I'm not sure why you'd > want to. Why are you taking the redundant disk off site? This smells > a bit like the old backup vs redundancy confusion. Any way, maybe LVM > snapshots are what you really want? They'll let you capture a whole, > consistent filesystem image while it's still in use. > > Steve. What's going on is this - we have a Windows SBS 2008 virtual machine running inside VMWare ESXi. VMWare ESXi is an interesting product but lacks the ability to show physically attached USB drives to any of the guest OSes. The original plan was for SBS 2008 to backup to the USB drives in-turn, so Monday would be on Disk 1, Tuesday on Disk 2, Wednesday on Disk 1, etc, etc. Installing SBS 2008 inside VMWare ESXi, however, put the kybosh on that plan. So now we have the SBS 2008 machine performing regular backups over the network to my machine which is setup to share USB Disk 1 with SAMBA. Since the only things that was mandatory was that one of the disks be taken off-site every night, I decided that Disk 1 should be the primary backup drive and Disk 2 should be a duplicate of it that can be taken off-site every night. I have already made it simple for whoever takes the drive home (usually me, but if I'm not in...) by putting an oversized icon on my desktop with "REMOVE BACKUP DRIVE" as the title - this points to a quick script that will establish if anything is currently using the "take home" drive and if not, unmount it and informs the user to turn off and disconnect the drive. There is a cron job that rsyncs the two drives together, but that can take a very long time (SBS 2008 backup dumps everything as a VHD file - so our backup is 1 file at 78GB with numerous small XML files surrounding it). What I was hoping was to have a smoother system where the two drives are essentially identical at the point where the "take home" drive gets removed, and can automatically reconcile the differences between the two when it gets reconnected. It's not a big issue as our current system does work, and we will be reviewing our backup procedures soon anyway. Cheers. Grant. :) -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html