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: Fri Mar 12 2010 - 08:54:07 GMT
To: drbd-user@lists.linbit.com

So, always the same problem without understanding why it works when
all iSCSI clients are connected to the same DRBD, and no way to
synchronize lvcreate/lvremove between clients on different DRBD hosts,
despite they are primary/primary..

I search a solution to the LVM side, but answers were "check your DRBD
replication link". :(

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

On Tue, Mar 9, 2010 at 3:46 PM, Olivier LAMBERT
<lambert.olivier@gmail.com> wrote:
>> 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.
>> __
>> please don't Cc me, but send to list   --   I'm subscribed
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>
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