Back Up (And Restore) LVM Partitions With LVM Snapshots - Page 2
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3 Create An LVM Snapshot Of /
Now it's time to create the snapshot of the /dev/server1/root volume. We will call the snapshot rootsnapshot:
lvcreate -L10G -s -n rootsnapshot /dev/server1/root
The output of
lvdisplay
should look like this:
server1:~# lvdisplay
--- Logical volume ---
LV Name /dev/server1/root
VG Name server1
LV UUID UK1rjH-LS3l-f7aO-240S-EwGw-0Uws-5ldhlW
LV Write Access read/write
LV snapshot status source of
/dev/server1/rootsnapshot [active]
LV Status available
# open 1
LV Size 9.30 GB
Current LE 2382
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:0
--- Logical volume ---
LV Name /dev/server1/swap_1
VG Name server1
LV UUID 2PASi6-fQV4-I8sJ-J0yq-Y9lH-SJ32-F9jHaj
LV Write Access read/write
LV Status available
# open 2
LV Size 464.00 MB
Current LE 116
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:1
--- Logical volume ---
LV Name /dev/server1/backups
VG Name server1
LV UUID sXq2Xe-y2CE-Ycko-rCoE-M5kl-E1vH-KQRoP6
LV Write Access read/write
LV Status available
# open 1
LV Size 30.00 GB
Current LE 7680
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:2
--- Logical volume ---
LV Name /dev/server1/rootsnapshot
VG Name server1
LV UUID 9zR5X5-OhM5-xUI0-OolP-vLjG-pexO-nk36oz
LV Write Access read/write
LV snapshot status active destination for /dev/server1/root
LV Status available
# open 1
LV Size 9.30 GB
Current LE 2382
COW-table size 10.00 GB
COW-table LE 2560
Allocated to snapshot 0.01%
Snapshot chunk size 8.00 KB
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:5
We want to mount /dev/server1/rootsnapshot on /mnt/server1/rootsnapshot, so we have to create that directory first:
mkdir -p /mnt/server1/rootsnapshot
Then we mount our snapshot:
mount /dev/server1/rootsnapshot /mnt/server1/rootsnapshot
Then we run
ls -l /mnt/server1/rootsnapshot/
This should show all directories and files that we know from our / partition:
server1:~# ls -l /mnt/server1/rootsnapshot/
total 132
drwxr-xr-x 2 root root 4096 2007-04-10 21:02 backups
drwxr-xr-x 2 root root 4096 2007-04-10 20:35 bin
drwxr-xr-x 2 root root 4096 2007-04-10 20:25 boot
lrwxrwxrwx 1 root root 11 2007-04-10 20:25 cdrom -> media/cdrom
drwxr-xr-x 13 root root 40960 2007-04-10 20:36 dev
drwxr-xr-x 57 root root 4096 2007-04-10 21:09 etc
drwxr-xr-x 3 root root 4096 2007-04-10 20:36 home
drwxr-xr-x 2 root root 4096 2007-04-10 20:26 initrd
lrwxrwxrwx 1 root root 28 2007-04-10 20:29 initrd.img -> boot/initrd.img-2.6.18-4-486
drwxr-xr-x 13 root root 4096 2007-04-10 20:34 lib
drwx------ 2 root root 16384 2007-04-10 20:25 lost+found
drwxr-xr-x 4 root root 4096 2007-04-10 20:25 media
drwxr-xr-x 2 root root 4096 2006-10-28 16:06 mnt
drwxr-xr-x 2 root root 4096 2007-04-10 20:26 opt
drwxr-xr-x 2 root root 4096 2006-10-28 16:06 proc
drwxr-xr-x 3 root root 4096 2007-04-10 20:42 root
drwxr-xr-x 2 root root 4096 2007-04-10 20:36 sbin
drwxr-xr-x 2 root root 4096 2007-03-07 23:56 selinux
drwxr-xr-x 2 root root 4096 2007-04-10 20:26 srv
drwxr-xr-x 2 root root 4096 2007-01-30 23:27 sys
drwxrwxrwt 2 root root 4096 2007-04-10 21:09 tmp
drwxr-xr-x 10 root root 4096 2007-04-10 20:26 usr
drwxr-xr-x 13 root root 4096 2007-04-10 20:26 var
lrwxrwxrwx 1 root root 25 2007-04-10 20:29 vmlinuz -> boot/vmlinuz-2.6.18-4-486
So our snapshot has successfullly been created!
Now we can create a backup of the snapshot on the /backups partition using our preferred backup solution. For example, if you like to do a file-based backup, you can do it like this:
tar -pczf /backups/root.tar.gz /mnt/server1/rootsnapshot
And if you like to do a bitwise backup (i.e. an image), you can do it like this:
dd if=/dev/server1/rootsnapshot of=/backups/root.dd
server1:~# dd if=/dev/server1/rootsnapshot of=/backups/root.dd
19513344+0 records in
19513344+0 records out
9990832128 bytes (10 GB) copied, 320.059 seconds, 31.2 MB/s
You could also use both ways to be prepared for whatever might happen to your /dev/server1/root volume. In this case, you should have two backups afterwards:
ls -l /backups/
server1:~# ls -l /backups/
total 9947076
drwx------ 2 root root 16384 2007-04-10 21:04 lost+found
-rw-r--r-- 1 root root 9990832128 2007-04-10 21:28 root.dd
-rw-r--r-- 1 root root 184994590 2007-04-10 21:18 root.tar.gz
Afterwards, we unmount and remove the snapshot to prevent it from consuming system resources:
umount /mnt/server1/rootsnapshot
lvremove /dev/server1/rootsnapshot
That's it, you've just made your first backup from an LVM snapshot.
