Aug
28
2012
Posted by ebal at
12:18:50
in blog, planet_Sysadmin
I am using LVM for storage to virtual machines.
One simply way to make backups (even if the machine is online) is through dd.
(but if you are using a database, online is out of question).
dd will backup the entire partition to a raw image.
Lets make an example:
# time dd if=/dev/vg01/winxp of=winxp.img bs=1024
5242880+0 records in
5242880+0 records out
5368709120 bytes (5,4 GB) copied, 111,164 s, 48,3 MB/s
So we have a 5Gb backup raw image with sparse files into.
If only there was a way to remove sparse files to reduce the size!
Wait … it does exist: virt-sparsify
# virt-sparsify winxp.img winxp.img.spars
...
Sparsify operation completed with no errors. Before deleting the old
disk, carefully check that the target disk boots and works correctly.
# ls -ltr
-rw-r--r-- 1 root root 5368709120 Αύγ 28 11:55 winxp.img
-rw-r--r-- 1 root root 5368709120 Αύγ 28 11:59 winxp.img.spars
# du -h *
5,1G winxp.img
3,1G winxp.img.spars
2gb sparse files have just removed !
Now you can compress the backup image to reduce the size even more:
# du -h winxp.img*
5,1G winxp.img
3,1G winxp.img.spars
1,4G winxp.img.spars.lrz
We can now remove winxp.img & winxp.img.spars (8.2Gb) from our backup storage.