[DRBD-user] Tape backups (yes, again)
juergen at kernkraft400.com
Fri Jun 12 12:08:09 CEST 2009
> -at backup time (2AM?):
> -stop drbd and heartbeat on the secondary
> -bring down the dedicated eth1 connection to the primary
> (leaving eth0 still up so I can get in if need be)
No need for that. When drbd is stopped it doesn't matter if your
replication link is up or not.
> -mount the sda4 partition (NOT the drbd0 device as drbd will be
> stopped) to it's normal position
Here is a crucial point. You should at least remount the filesystem on
the primary read-only - to prevent your filesystem's metadata AND the
actual data from being corrupted because you pulled the plug in the
> -run my usual tape backup routine
> -unmount sda4 again
> -bring eth1 back up
> -start drbd and heartbeat again
This should work.
> I am thinking that in this way my users will still see NO downtime
> of the primary resource (unless of course there is a hardware
> failure during the tape backup while the secondary is offline!), and
> I still get a tape backup that is quite current.
Your assumtions seem to be correct to me.
> Could it really be this simple? We don't use lvm at all, just plain
> old ext3 file systems, so I believe this negates the whole lvm
> snapshot and then back that up dicussion I have seen here in the
> lists. What are your thoughts? Currently we implement
I don't understand why you seem to insist on going the complicated way
when you can have this which significantly lower downtime just by
using lvm and snapshots. (disks <-> LVM <-> DRBD)
With using lvm on both ends you could even run your tape backup from
the primary or the secondary (important if you have a hardware failure
and can't replace the machine in less than one day) without modifying
anything on your setup.
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