[Lustre-discuss] Removing an OST

[Andreas Dilger]

On Jan 19, 2009  10:18 +0100, Heiko Schroeter wrote:
> Is it possible to get these infos into the documentation as it may hit one or 
> the other in the lustre community ?

Yes, we always welcome improvements to the documentation.  As you can
imagine, I rarely need to reference the documentation myself, so I don't
know whether it is up-to-date or not, or if it explains a given topic
clearly enough or not.

> The manual only gives two 'general' approaches one of which is to 'deactivate 
> the OST', the other one just says to remount the partition with "ext3" which 
> didn't work for the lustre partitions here.
> 
> Maybe something like (if it is correct):
> 
> Removing/Replacing an OST with recreating the files into lustre:
> Deactivate the OST for the MDS only, using 'set_param' instead 
> of 'config_param', so clients are able to read the data. i.e:
> 
> >  lctl  set_param  foo-OST000d-osc.active=0

This should be "lctl set_param osc.foo-OST000d-osc.active=0

> Copy the data on a client to a temp storage outside (does it has to be 
> outside?) the lustre system and 'move' them back into lustre to create new 
> inodes entries on the MDS.

Actually, it should NOT be on storage outside Lustre in this case.

> > 	cp .../dat.file .../dat.file.tmp
> > 	mv .../dat.file.tmp .../dat.file

> After moving all files the OST can be permantly set inactive with.i.e.:
> >  lctl  config_param  foo-OST000d-osc.active=0

Correct.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.