[K12OSN] BackupPPC Question

Les Mikesell les at futuresource.com
Wed Apr 27 21:07:04 UTC 2005


On Wed, 2005-04-27 at 12:27, Burroughs, Henry wrote:

> What I want is BackupPPC (or a similar rsync trick to keep multiple
> days/weeks/months worth of backups) and a way to mirror/replicate the
> backed-up data onto one or two removable drives (ie: an external firewire
> drive) so that way I can take a copy of the data (or a good chunk of it)
> home with me everynight (plug it in the morning and it updates itself)...
> and then once I get my offsite location, it will act as one of those 
> "removable" drives and I'll have a 3rd copy.  So basically, i'm looking
> for a process to replicate the BackupPPC data to X number of removable
> drives/and or other storage locations.

I'm doing exactly that with a 250 gig IDE drive and 3 external
USB/firewire drives that I periodically swap and re-sync.  I'm not
completely happy with the process but it beats anything else that
I have tried so far.  The downside is that it takes some manual
intervention to break and re-sync the mirror and about 8 hours
to complete, but I only do the swap once a week.  The good parts
are that except for a quick unmount/remount of the partition, the
machine keeps working normally during the re-sync and it doesn't
really care if the 2nd drive is attached or not.  I'm connecting
to the server over firewire, but can mount the offline drive
on my laptop via USB and a copy of backuppc there will do a restore.

I just did an upgrade from FC1 to FC3 on the server and have crashed
a few times since, always with the firewire mirror running.  FC1 was
rock-solid (but didn't automatically detect the firewire device) so I
may go back or try ubuntu.  FC3 seems to auto-detect the drive when
plugged, but not during a reboot which is what I really wanted so
the raid would be detected and not have to resync.

> P.S.  Someone on another list had said something about rsync -H taking
> an extremely long time to compute symlinks...any experience w/ that?

Yes, the disk that takes 8 hours to raid-sync would take many days to
do a file based copy.  There are just no efficient ways to handle the
number of hardlinks that backuppc uses.  The other technique I've seen
mentioned on the backkuppc list that might work even better than raid
is to put the server filesystem on LVM.  Then you can unmount it
momentarily, create an LVM snapshot and remount.  Then you can do an
image copy with dd from the frozen snapshot to a matching partition
on an external drive.  The person doing it said this takes a couple of
hours with the machine continuing to work.

-- 
  Les Mikesell
   les at futuresource.com




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