[Lustre-discuss] Deactivate OST

[Heiko Schröter]

On Donnerstag 24 September 2009 12:58:35 Brian J. Murrell wrote:

Get device list on MDS:
lctl dl

Disabling write only. Read on clients possible.:
lctl set_param osc.lustre-OST000d-osc.active=0

Disable read/write (disabling device permanently):
lctl --device 18 conf_param lustre-OST000d.osc.active=0
(18 and OST000d) has to be replaced by your stuff of course)

Watchout:
A bug in 'lfs' (still not fixed) will not step over an deactivated device. We do use a patched version here to get around. Version 1.6 and 1.8.
https://bugzilla.lustre.org/show_bug.cgi?id=18329

All commands on MDS.
Thanks to Andreas Dilger some time ago who pointed that out.

Regards
Heiko

> On Thu, 2009-09-24 at 11:31 +0200, Frank Heckes wrote:
> > Hi all,
> 
> Hi,
> 
> > sorry if this has been answered before, but I could find only one
> > un-answered question concerning this topic in the archive.
> 
> Hrm.  Strange, as I believe this has been answered in the archive many,
> many times.  I believe the answer to this is in the manual too.
> 
> > If I like to deactivate write operation for an OST temporary, but allow
> > clients to read still data from the OST, disabling the OST on the MDS
> > will do the job as described in the admin guide.
> 
> Not quite.  Disabling on the MDS only disables "new allocation", not
> write.  That means that new objects won't be allocated to files from the
> deactivated OST.  Writes to existing objects will still be allowed.
> 
> > In case an OST was lost and clients shouldn't contact the OST anymore
> > (if OST is damaged irreversible) even for read operation, could I
> > execute the 'lcl --device <id> deactivate' command also on the clients?
> 
> Hrm.  I usually fiddle with the proc file directly on this, but suffice
> it to say that whatever operation you are using on the MDS to deactivate
> an OST can be used on the client to return EIOs when a given OST is
> accessed.
> 
> > Or is this action superfluous since the client will receive EIO's
> > anyway?
> 
> No.  The client will only receive EIOs if that client has deactivated
> the OST.
> 
> > Many thanks in advance.
> 
> NP.
> 
> b.
> 
> 

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