[Lustre-discuss] Draining an OST (avoid new object creation)

[Brock Palen]

We want to start draining and OST.  I looked online and I found

lctl --device ## deactivate

And:
lctl conf_param nobackup-OST0001.osc.active=0

The first one does what we want but does not survive a reboot.
The second survives a reboot but does not let files already on an OST to be access and modified.

We want users to be able to use any files already on that OST (until the outage when we move them).  Modify expand etc.  But new files should not be created there.

Any thoughts on how to do this would be great.

We cannot put the deactivate command in rc.local because the MDS nodes are managed by heartbeat and thus would not always be ran when the filesystem becomes active.  So we are looking for a survive reboot way to avoid new object creation on a set of old OST's. 

Thanks!

Brock Palen
www.umich.edu/~brockp
Center for Advanced Computing
brockp at umich.edu
(734)936-1985