[DRBD-user] migrating to a larger DRBD device

campbellm at cia.com.au campbellm at cia.com.au
Mon Oct 11 08:22:45 CEST 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I have a question regarding migrating a DRBD device to a one of a
different size (in this case, a larger partition), and do this without
stopping any services.

I have been experimenting with this and have found that, after resizing
a device and then bring it up as a primary, it syncs and mounts the DRBD
device ok, except that it creates it as the old size even though the
lower level device on which it is mounted is much larger. 

My guess is this is due to meta-data. Apart from maybe using a setup where
the meta-data device is on a separate device, what would be the best way
to do such a migration? One way might be to use 'tar' or 'cp' (maybe
dump?) to backup up the existing DRBD device to somewhere else, and then 
shut the machines down, create the new DRBD devices (either on a larger
partition or a new disk), run drbdsetup, make the filesystem, and copy
the data back.

Is this pretty much the best way? I assume it cannot be done using the
'syncing' functions of DRBD, so that you could get away without having a
service outage. Again, this assumes an 'internal' meta-data, although I
guess that wouldn't make a difference anyway.

Cheers for any pointers.


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