Lvm snapshot
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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".
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