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: Sat Mar 13 2010 - 09:31:04 GMT
To: drbd-user@lists.linbit.com

Thank you everyone !
I'll do some tests monday and tell you if I could fix that stuff.

Regards,

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

On Fri, Mar 12, 2010 at 11:16 PM, Lars Ellenberg
<lars.ellenberg@linbit.com> wrote:
> On Fri, Mar 12, 2010 at 10:38:27AM +0100, Olivier LAMBERT wrote:
>> 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 ?
>
> No.
> Above DRBD layer.
> Not below.
>
> I'm still guessing here.
>
> But here is what I _know_.
> 1)
>  DRBD replicates whatever is written to it.
>  This is proven in the real world.
>  LINBIT would not exist if it did not.
>  So that cannot be the problem.
>
> 2)
>  You observe that data written on some iscsi client
>  to a target on top of DRBD is not (immediately) visible
>  from some other iscsi client.
>  This I have to believe you.
>
> Which leaves me at:
> either the data in question does not reach DRBD,
> or someone who is supposed to read from DRBD does not,
> because some layer in between servers "cached" data
> which happens to be stale content.
>
> Does that make sense?
>
>> Sorry, but sometimes only "cache consistency" is too vague for me...
>
> We also do consulting, workshops,
> project guidance and monitoring,
> and in general support ;)
>
> --
> : 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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