[Lustre-discuss] Removing an OST

[Heiko Schroeter]

Hello list,

the manual (May 2008) describes on page 4-14 how to remove an OST from LUSTRE.
Its says "deactivate the OST (make it read-only).

Hm, i'am a bit puzzled here.
When i deactivate the OST on the MDS using
'lctl --device 18 conf_param foo-OST000d.osc.active=0' the device is 
deactivated but i cannot read any files from it any longer. Quite logical.

On the other hand using lctl "readonly" option is specified as "dangerous".

So what is the correct approach of replacing an OST and/or what is the correct 
syntax for lctl (or whatever command) putting a device in read-only mode ?

When the OST is in read-only mode and i "recopy" the file over the original 
one what happens to the directory structure ? Is it necessary to recreate 
it ? Or is it enough to do something like this (mentioned under 3. on the 
above lustre manual page):

cp /lustrefs/dir1/foo/dat.file    /tmp/.
cp /tmp/dat.file     /lustrefs/dir1/foo/.

Sorry if this has been asked before but i want to be sure not to break our 
productional system.

Thanks and Regards
Heiko