Lustre 1.6 Operations Manual

How do I backup / restore a Lustre filesystem?
Several types of Lustre backups are available.
CLIENT FILE SYSTEM-LEVEL BACKUPS
It is possible to back up Lustre filesystems from a client (or many clients in parallel
working in different directories), via any number of user-level backup tools like tar,
cpio, Amanda, and many enterprise-level backup tools. However, due to the very
large size of most Lustre filesystems, full backups are not always possible. Doing
backups of subsets of the filesystem (subdirectories, per user, incremental by date,
etc.) using normal file backup tools is still recommended, as this is the easiest
method from which to restore data.
TARGET RAW DEVICE-LEVEL BACKUPS
In some cases, it is desirable to do full device-level backups of an individual MDS or
OST storage device for various reasons (before hardware replacement, maintenance
or such). Doing full device-level backups ensures that all of the data is preserved in
the original state and is the easiest method of doing a backup.
If hardware replacement is the reason for the backup or if there is a spare storage
device then it is possible to just do a raw copy of the MDS/OST from one block
device to the other as long as the new device is at least as large as the original device
using the command:
dd if=/dev/{original} of=/dev/{new} bs=1M
If hardware errors are causing read problems on the original device then using the
command below allows as much data as possible to be read from the original device
while skipping sections of the disk with errors:
dd if=/dev/{original} of=/dev/{new} bs=4k conv=sync,noerror
Even in the face of hardware errors, the ext3 filesystem is very robust and it may be
possible to recover filesystem data after e2fsck is run on the new device.
TARGET FILE SYSTEM-LEVEL BACKUPS
In other cases, it is desirable to make a backup of just the file data in an MDS or OST
filesystem instead of backing up the entire device (e.g., if the device is very large but
has little data in it, if the configuration of the parameters of the ext3 filesystem need
to be changed, to use less space for the backup, etc).
In this case it is possible to mount the ext3 filesystem directly from the storage
device and do a file-level backup. Lustre MUST BE STOPPED ON THAT NODE.
To back up such a filesystem properly also requires that any extended attributes
(EAs) stored in the filesystem be backed up, but unfortunately current backup tools
do not properly save this data so an extra step is required.
Appendix D Lustre Knowledge Base D-13