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<TITLE>Re: [Lustre-discuss] Multiple MDTs with Lustre 1.6?</TITLE>
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Heheheh, I figured.<BR>
<BR>
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?<BR>
<BR>
Klaus<BR>
<BR>
On 10/12/07 10:38 AM, "Kilian CAVALOTTI" <kilian@stanford.edu>did etch on stone tablets:<BR>
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</SPAN></FONT><BLOCKQUOTE><FONT FACE="Verdana, Helvetica, Arial"><SPAN STYLE='font-size:12.0px'>Hi Klaus,<BR>
<BR>
On Friday 12 October 2007 10:18:49 am Klaus Steden wrote:<BR>
> I have redundant MDS/MDT servers, and when generating their<BR>
> /etc/fstab files, I have them both list the MDT volume under their<BR>
> mounted drives (so that they both mount the metadata volume). Being a<BR>
> bit of a neophyte, I¹m not sure if this is the right thing to do. Is<BR>
> this going to cause a problem in future? What are the possible<BR>
> consequences of both hosts mounting the same metadata volume<BR>
> simultaneously? How do the OSTs handle this situation?<BR>
<BR>
I'm afraid mounting the MDT device on both hosts is a very bad idea. Not<BR>
only for Lustre, but in a general fashion, unless you're using some<BR>
specific filesystem which has been designed in that goal (like OCFS2 or<BR>
GFS). A 'standard' filesystem like ext3 can't handle simultaneous<BR>
writes from different hosts at the same time. It's likely to cause<BR>
heavy data corruption in the MDT filesystem, and the OSTs are not<BR>
supposed to deal with anything like that.<BR>
<BR>
You can still reference the MDT device in both MDS' fstab, but be sure<BR>
you add the "noauto" option so the volume won't be mounted at boot. It<BR>
will be the high-availability provider's job (likely heartbeat) to deal<BR>
with mounting the MDT device on the active MDS.<BR>
<BR>
See<BR>
<a href="http://manual.lustre.org/manual/LustreManual16_HTML/DynamicHTML-08-1.html#wp1035482">http://manual.lustre.org/manual/LustreManual16_HTML/DynamicHTML-08-1.html#wp1035482</a><BR>
for more details.<BR>
<BR>
Cheers,<BR>
--<BR>
Kilian<BR>
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