Lustre 1.6 Operations Manual

9. Format the new device. The easiest way to get the optimal ext3 parameters is to
use lconf --reformat {config}.xml ONLY ON THE NODE being restored.
If there are multiple services on the node, then this reformats all of the devices on
that node and should NOT be used. Instead, use the step below:
■ For MDS filesystems, use: mke2fs -j -J size=400 -I {inode_size} -i 4096 {dev}
where {inode_size} is at least 512, and possibly larger if you have a default,
stripe count > 10 (inode_size = power_of_2_>=_than(384 + stripe_count * 24)).
■ For OST filesystems, use: mke2fs -j -J size=400 -I 256 -i 16384 {dev}
10. Enable ext3 filesystem directory indexing. Type:
tune2fs -O dir_index {dev}
11. Mount the filesystem. Type:
■ For 2.4 kernels use: mount -t ext3 {dev} /mnt/mds
■ For 2.6 kernels use: mount -t ldiskfs {dev} /mnt/mds
12. Change to the new filesystem mount point. Type:
cd /mnt/mds
13. Restore the filesystem backup. Type:
tar xzvpf {backup file}
14. Restore the filesystem EAs. Type:
setfattr --restore=ea.bak
15. Remove the (now invalid) recovery logs. Type:
rm OBJECTS/* CATALOGS
Again, the restore of the EAs (described in Step 6) is not currently required for OST
devices, but this may change in the future.
If the filesystem was used between the time the backup was made and when it was
restored, then the "lfsck" tool (part of Lustre e2fsprogs) can be run to ensure the
filesystem is coherent. If all of the device filesystems were backed up at the same
time after the whole Lustre filesystem was stopped this is not necessary. The
filesystem should be immediately usable even if lfsck is not run, though there will be
IO errors reading from files that are present on the MDS but not the OSTs, and files
that were created after the MDS backup will not be accessible/visible.
Appendix D Lustre Knowledge Base D-15