Lustre 1.6 Operations Manual

15.1.3.2 Backing Up an OST File
Follow the same procedure as Backing Up an MDS File (except skip Step 4) and, for
each OST device filesystem, replace mds with ost in the commands.
15.2 Restoring from a File-level Backup
To restore data from a file-level backup, you need to format the device, restore the
file data and then restore the EA data.
1. Format the device. To get the optimal ext3 parameters, run:
$ mkfs.lustre --fsname {fsname} --reformat --mgs|mdt|ost /dev/sda
Caution – Only reformat the node which is being restored. If there are multiple
services on the node, do not perform this step as it can cause all devices on the node
to be reformatted. In that situation, follow these steps:
For MDS filesystems, run:
mke2fs -j -J size=400 -I {inode_size} -i 4096 {dev}
where {inode_size} is at least 512 and possibly larger if the default stripe count is
> 10 (inode_size = power_of_2_>=_than(384 + stripe_count * 24)) 2
For OST filesystems, run:
mke2fs -j -J size=400 -I 256 -i 16384 {dev}”
2. Enable ext3 filesystem directory indexing.
tune2fs -O dir_index {dev}
2. In the mke2fs command, the -I option is the size of the inode and the -i option is the ratio of inodes to space in
the filesystem: inode_count = device_size / inode_ratio. Set the -i option to 4096 so Extended Attributes
(EAs) can fit on the inode as well. Otherwise, you have to make an indirect allocation to hold the EAs, which
impacts performance owing to the additional seeks.
15-4 Lustre 1.6 Operations Manual • September 2008