drbd-user March 2010 archive
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drbd-user: Re: [DRBD-user] Detection of Logical Volume on nested

Re: [DRBD-user] Detection of Logical Volume on nested LVM

From: Olivier LAMBERT <lambert.olivier_at_nospam>
Date: Tue Mar 09 2010 - 14:46:10 GMT
To: drbd-user@lists.linbit.com

> It just replicates whatever you write to it, no more, no less.

That's why I don't understand why it works fine when LVM clients are
connected on the same DRBD server, and it doesn't work when each
client is on separate DRBD server (despite replication is working).
Can you explain this behaviour ?

Furthermore, I do some tests with cLVM. My cluster is working, I can
create pv and vg on one node, but the other can't see it. Then, when I
try to create a LV, cLVM says :
lvcreate -L82M -n testvol vg_xen
  Rounding up size to full physical extent 84,00 MB
  Error locking on node ad37864: Volume group for uuid not found:
1xgSmqky8beMkIQSGqYQ0fSC6IdOBOJEg46qEeWY9eV9njYJ2B9zxJwyXIaSHs3h
  Aborting. Failed to activate new LV to wipe the start of it.

Sorry if I miss someting...

Olivier
XO Project
http://xen-orchestra.com

On Tue, Mar 9, 2010 at 3:09 PM, Lars Ellenberg
<lars.ellenberg@linbit.com> wrote:
> On Tue, Mar 09, 2010 at 11:39:34AM +0100, Olivier LAMBERT wrote:
>> Hmmm. I like riddles, so I'm going to google this. Is there any simple
>> solutions, in example force drbd to deal with that ?
>
> You need to "force" your application stuff (and, yes, in this context
> lvm is an application) do deal with that, and cLVM would be the means
> to do that, i.e. coordinate.  Possibly you even need to start earlier,
> and fix your iSCSI target configuration.
>
> There is nothing to force DRBD to do in this context.
> It just replicates whatever you write to it, no more, no less.
>
> If you have caches on "the way" to "the other client"
> that happen to happily cache stale content (are "incoherent"),
> there is nothing DRBD can do about it.
>
> --
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
>
> DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
> __
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