[Lustre-discuss] Multiple MDTs with Lustre 1.6?

[Klaus Steden]

Heheheh, I figured.

What about mounting OST targets from multiple hosts, i.e. OST0000 and
OST0001 on both oss-0-0 and oss-0-1? Just as bad?

Klaus

On 10/12/07 10:38 AM, "Kilian CAVALOTTI" <kilian at stanford.edu>did etch on
stone tablets:

> Hi Klaus,
> 
> On Friday 12 October 2007 10:18:49 am Klaus Steden wrote:
>> > I have redundant MDS/MDT servers, and when generating their
>> > /etc/fstab files, I have them both list the MDT volume under their
>> > mounted drives (so that they both mount the metadata volume). Being a
>> > bit of a neophyte, I¹m not sure if this is the right thing to do. Is
>> > this going to cause a problem in future? What are the possible
>> > consequences of both hosts mounting the same metadata volume
>> > simultaneously? How do the OSTs handle this situation?
> 
> I'm afraid mounting the MDT device on both hosts is a very bad idea. Not
> only for Lustre, but in a general fashion, unless you're using some
> specific filesystem which has been designed in that goal (like OCFS2 or
> GFS). A 'standard' filesystem like ext3 can't handle simultaneous
> writes from different hosts at the same time. It's likely to cause
> heavy data corruption in the MDT filesystem, and the OSTs are not
> supposed to deal with anything like that.
> 
> You can still reference the MDT device in both MDS' fstab, but be sure
> you add the "noauto" option so the volume won't be mounted at boot. It
> will be the high-availability provider's job (likely heartbeat) to deal
> with mounting the MDT device on the active MDS.
> 
> See
> http://manual.lustre.org/manual/LustreManual16_HTML/DynamicHTML-08-1.html#wp10
> 35482
> for more details.
> 
> Cheers,
> --
> Kilian
> 


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