Lustre 1.6 Operations Manual

Client mount for foo:
mount -t lustre mgsnode@tcp0:/foo /mnt/work
Client mount for bar:
mount -t lustre mgsnode@tcp0:/bar /mnt/scratch
4.2.3 Other Configuration Tasks
This section describes other Lustre configuration tasks.
4.2.3.1 Removing an OST
In Lustre 1.6, an OST can be permanently removed from a filesystem. Any files that
have stripes on the removed OST will, in the future, return EIO.
$ mgs> lctl --device conf_param testfs-OST0001.osc.active=0
This tells any clients of the OST that it should not be contacted; the OSTs current
state is irrelevant.
To remove an OST:
1. Deactivate the OST (make it read-only) on the MDS so no new objects are
allocated to it.
Use lctl --device to deactivate on the MDS and clients to
deactivate an OST temporarily. 2
2. Use lfs find to discover all files that have objects residing on the
deactivated OST.
3. Copy these files to a new location and then move them back to their original
location to force their object re-creation on the active OSTs and the object
deletion on the OST to be removed.
To restore the OST:
1. Make sure the OST is running.
2. Run this command:
$ mgs> lctl --device conf_param testfs-OST0001.osc.active=1
2. Do not use lctl conf_param to deactivate the OST. It permanently sets a parameter in the filesystem
configuration.
Chapter 4 Lustre Installation 4-13