Difference between revisions of "Lvm snapshot"
From Finninday
(New page: First, I added a new disk and did a pvcreate on it. Then I added the new disk to the same volume group that the root partition is in, namely "Ubuntu". Command to create an lvm snapshot i...) |
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| + | See http://www.howtoforge.com/linux_lvm_snapshots for reference. | ||
| + | |||
First, I added a new disk and did a pvcreate on it. Then I added the new disk to the same volume group that the root partition is in, namely "Ubuntu". | First, I added a new disk and did a pvcreate on it. Then I added the new disk to the same volume group that the root partition is in, namely "Ubuntu". | ||
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Connect the USB drive where the backup will be stored. | Connect the USB drive where the backup will be stored. | ||
| + | <pre> | ||
| + | root@weasel:/media# df | ||
| + | Filesystem 1K-blocks Used Available Use% Mounted on | ||
| + | /dev/mapper/Ubuntu-root | ||
| + | 234052488 111205240 110957996 51% / | ||
| + | varrun 514528 408 514120 1% /var/run | ||
| + | varlock 514528 0 514528 0% /var/lock | ||
| + | udev 514528 92 514436 1% /dev | ||
| + | devshm 514528 0 514528 0% /dev/shm | ||
| + | lrm 514528 43040 471488 9% /lib/modules/2.6.24-19-generic/volatile | ||
| + | /dev/mapper/vg00-big 240361984 195076932 33075288 86% /big | ||
| + | /dev/sdd1 484535504 238344264 221772040 52% /media/disk | ||
| + | </pre> | ||
| + | The USB disk was automounted on /media/disk. | ||
Do the backup. | Do the backup. | ||
| + | <pre> | ||
| + | root@weasel:/media/disk# time dd if=/dev/Ubuntu/root-snap of=/media/disk/weasel-root.dd | ||
| + | 475570176+0 records in | ||
| + | 475570176+0 records out | ||
| + | 243491930112 bytes (243 GB) copied, 13529.5 s, 18.0 MB/s | ||
| + | |||
| + | real 225m29.539s | ||
| + | user 3m0.511s | ||
| + | sys 111m46.531s | ||
| + | </pre> | ||
| + | That's about 4 hours for 250G at 18M/sec. If root was only 5G it should be more like 5 minutes. | ||
| + | |||
| + | Verify the backup and disconnect the USB drive. | ||
Destroy the snapshot. | Destroy the snapshot. | ||
| + | <pre> | ||
| + | root@weasel:/media/disk# lvremove /dev/Ubuntu/root-snap | ||
| + | File descriptor 5 left open | ||
| + | File descriptor 6 left open | ||
| + | File descriptor 7 left open | ||
| + | File descriptor 8 left open | ||
| + | Do you really want to remove active logical volume "root-snap"? [y/n]: y | ||
| + | Logical volume "root-snap" successfully removed | ||
| + | </pre> | ||
Latest revision as of 14:52, 25 June 2008
See http://www.howtoforge.com/linux_lvm_snapshots for reference.
First, I added a new disk and did a pvcreate on it. Then I added the new disk to the same volume group that the root partition is in, namely "Ubuntu".
Command to create an lvm snapshot in order to do a backup of the root partition.
lvcreate -L250G -s -n root-snap /dev/Ubuntu/root
root@weasel:~# lvscan File descriptor 5 left open File descriptor 6 left open File descriptor 7 left open File descriptor 8 left open ACTIVE '/dev/vg00/big' [232.88 GB] inherit ACTIVE Original '/dev/Ubuntu/root' [226.77 GB] inherit ACTIVE '/dev/Ubuntu/swap_1' [5.88 GB] inherit ACTIVE Snapshot '/dev/Ubuntu/root-snap' [250.00 GB] inherit
Connect the USB drive where the backup will be stored.
root@weasel:/media# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/Ubuntu-root
234052488 111205240 110957996 51% /
varrun 514528 408 514120 1% /var/run
varlock 514528 0 514528 0% /var/lock
udev 514528 92 514436 1% /dev
devshm 514528 0 514528 0% /dev/shm
lrm 514528 43040 471488 9% /lib/modules/2.6.24-19-generic/volatile
/dev/mapper/vg00-big 240361984 195076932 33075288 86% /big
/dev/sdd1 484535504 238344264 221772040 52% /media/disk
The USB disk was automounted on /media/disk.
Do the backup.
root@weasel:/media/disk# time dd if=/dev/Ubuntu/root-snap of=/media/disk/weasel-root.dd 475570176+0 records in 475570176+0 records out 243491930112 bytes (243 GB) copied, 13529.5 s, 18.0 MB/s real 225m29.539s user 3m0.511s sys 111m46.531s
That's about 4 hours for 250G at 18M/sec. If root was only 5G it should be more like 5 minutes.
Verify the backup and disconnect the USB drive.
Destroy the snapshot.
root@weasel:/media/disk# lvremove /dev/Ubuntu/root-snap File descriptor 5 left open File descriptor 6 left open File descriptor 7 left open File descriptor 8 left open Do you really want to remove active logical volume "root-snap"? [y/n]: y Logical volume "root-snap" successfully removed
