[DRBD-user] dual primary mode with which FS

Lars Ellenberg lars.ellenberg at linbit.com
Wed Mar 24 10:59:32 CET 2010

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

On Wed, Mar 24, 2010 at 10:42:29AM +0100, Stefan Seifert wrote:
> On Wednesday 24 March 2010 09:50:44 Christian Iversen wrote:
> > Are you sure that LVM can create the snapshot without updating the
> > metadata on the device? Because that's not allowed.
> Actually it never occurred to me that LVM could change the volume. But I could 
> not imagine any reason for it to do that. And indeed I'm using snapshots for 
> backing up my DRBD volumes without any problem, so my guess should be correct.

LVM of course updates its metadata.
But in this case, that is not on DRBD: you do the snapshot below DRBD
to use it on the secondary.

You may of course also use DRBD as PV,
in which case you could snapshot "above" drbd,
and have your snapshots replicated as well.
But you'd have a hard time accessing them on a secondary
(read: currently that would be impossible to do,
and once clustered snapshots are supported properly, you'd still need a
complex dual-primary setup with cLVM and whatnot)

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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