Lustre 1.6 Operations Manual

cfs21:~# mount -t lustre /dev/volgroup/OST0 /mnt/ost
cfs21:~# mount -t lustre cfs21:/main /mnt/main
15.3.2 Backing Up New Files to the Backup Filesystem
This is your nightly backups of your real on-line Lustre filesystem.
cfs21:~# cp /etc/passwd /mnt/main
cfs21:~# cp /etc/fstab /mnt/main
cfs21:~# ls /mnt/main
fstab passwd
15.3.3 Creating LVM Snapshot Volumes
Whenever you want to make a "checkpoint" of your Lustre filesystem, you create
LVM snapshots of all the target disks in "main". You must decide the maximum size
of a snapshot ahead of time,however you can dynamically change this later. The size
of a daily snapshot is dependent on the amount of data you change daily in your online
filesystem. It is also likely that a two-day old snapshot will be twice as big as a
one-day old snapshot.
You can create as many snapshots as you have room for in your volume group. You
can also dynamically add disks to the volume group if needed.
The snapshots of the target disks (MDT, OSTs) should be taken at the same point in
time, making sure that cronjob updating "main" is not running, since that is the only
job writing to the disks.
cfs21:~# modprobe dm-snapshot
cfs21:~# lvcreate -L50M -s -n MDTb1 /dev/volgroup/MDT
Rounding up size to full physical extent 52.00 MB
Logical volume "MDTb1" created
cfs21:~# lvcreate -L50M -s -n OSTb1 /dev/volgroup/OST0
Rounding up size to full physical extent 52.00 MB
Logical volume "OSTb1" created
After the snapshots are taken, you can continue to back up new/changed files to
"main". The snapshots will not contain the new files.
cfs21:~# cp /etc/termcap /mnt/main
cfs21:~# ls /mnt/main
fstab passwd termcap
15-8 Lustre 1.6 Operations Manual • September 2008