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 - 09:38:27 GMT
To: drbd-user@lists.linbit.com

Ok, so after reading that :
http://lists.linbit.com/pipermail/drbd-user/2008-June/009636.html
and
http://archives.free.net.ph/message/20090319.001657.5a0095e9.en.html

Where you talking about cache consistency, you think the problem might
be on the Dell PowerVault MD1000 SAS ?
So you think the cache of the array is not really written on the disk
(because other DRBD can't see it, because no blocks are written), and
that's why it doesn't work.

Great, but I don't know how to deal with that. Disable cache on the
RAID controller ? (the array) Check with MD5 like in first link I've
posted ?

Sorry, but sometimes only "cache consistency" is too vague for me...

Regards,

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

On Fri, Mar 12, 2010 at 10:20 AM, Lars Ellenberg
<lars.ellenberg@linbit.com> wrote:
> On Fri, Mar 12, 2010 at 09:54:07AM +0100, Olivier LAMBERT wrote:
>> 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". :(
>
> CHECK YOUR CACHE CONSISTENCY.
>
> As I told you before,
>
>> >> 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.
>
> (and cLVM would not be able to do anything about it either).
>
> So.
> Please. Check. That.
>
> --
> : 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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