using rsync for incremental raw disk backup?

Daniel Pocock daniel at
Sun Jan 1 03:16:07 MST 2012

I use off-site replication (rsync), but having backups on tape is also

The tape backup software offers a very thorough incremental and
differential backup solution for UNIX filesystems, but for Windows
filesystems that must be recoverable to a bootable state, I feel that
only raw filesystem dumps are trustworthy.

One strategy that comes to mind:

a) rsync the raw device (an LVM2 volume containing NTFS) to an LV on my
backup machine (which is connected via WAN)
b) full backup to tape of the raw volume
c) on the backup machine, take an LVM snapshot of the LV that was backed up
d) on a regular basis, shut down the Windows VM and rsync the
differences over to the backup machine
e) at this point, I would like to send a differential backup to tape
(i.e. the difference between what rsync gave me and the snapshot from
step (c)) - not a full dump of the raw device on every tape

My two questions then:
- for step (d), can the rsync algorithm be used to mirror raw devices?
- for step (e), can the rsync algorithm be used to compare the raw
devices (the updated LV and the snapshot) and generate something like a
standalone diff file that can go to tape?

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