[DRBD-user] Problem mounting lvm snapshot
ff at mpexnet.de
Wed Oct 27 09:13:55 CEST 2010
On 10/26/2010 11:20 PM, Lewis Donzis wrote:
> We'd like to be able to make backups from our DRBD secondary by mounting
> the underlying filesystems. After some searching, this appears to be a
> relatively common discussion: running DRBD on top of LVM, making a
> snapshow of the backing LV on the secondary, and mounting the snapshot LV.
> As has been discussed, it's not perfect, but it should produce reasonable
> results most of the time, at least no worse than if there had been a power
> So, I'm sorry if this is a silly question, but I can't seem to get this to
> work. It appears that DRBD permanently prevents mounting the backing
> device (or its snapshot) because "drbdadm create-md" function modifies the
> filesystem so that it can no longer be mounted except via the /dev/drbdX
> device. In particular, attempting to mount a snapshot, or detaching DRBD
> from the backing device and attempting to mount the file system, or even
> just attempting to mount the backing device after create-md has run,
> results in:
> mount: unknown filesystem type 'drbd'
what are the options you try and mount the snapshot?
mount should not assume a "drbd" filesystem type. You probably use bad
options or have a faulty fstab. If all else fails, use
mount -t <correct_fs>.
Also, your filesystem should have been created after create-md, on the
/dev/drbdX device (unless I'm gravely mistaken). In any case, the fs has
no notion of DRBD whatsoever, as DRBD works on the block layer of things.
More information about the drbd-user