> Does anyone know the reason why you cannot snapshot
powered off machines?
I have learned that backups of VMware Windows-XP guests
under Linux are easy, and seem reliable, without starting or
restarting VMware or the VM. The method we use requires
that the Windows NTFS filesystem be set up as a single
undivided file; this is an option when you set up the guest
OS in a VM, but it's not the default.
I mount this file as an ntfs-3g filesystem. Here's a line
from my /etc/fstab:
/vmware/winxpclone/Windows\040XP\040Professional-cl1-flat.vmdk
/mnt/vmdk-srn ntfs-3g umask=0002,loop,offset=32256,ro 0 0
Note the "-flat" in the filename; VMware adds that suffix
when the filesystem is not divided into several files. Also
note the "offset=32256" option. I found that trick on the
web somewhere.
The only other thing to be aware of is that the ntfs-3g
filesystem should be unmounted (if mounted) and mounted
again (there's no remount option in ntfs-3g) just before
dumping it. If you don't do that, changes to the file
system made by Windows since the last time it was mounted
under Linux will cause errors. And if the VM is busy during
the dump, there may still be problems, but we haven't had
any, I guess because our VMs have nothing to do when we're
asleep (often they're not even running) and the backups are
running. Anyway, it's not very different, really, from any
situation in which a dump is being made of an active
filesystem. (It is a little different, of course.)
I also take the precaution of dumping the whole NTFS
filesystem file, raw, when I do a level 0, just in case.
It makes total restoration very simple indeed -- and simpler
than it could ever be under Windows ordinarily.
Incrementals seem to work quite well, btw, under ntfs-3g.
I'm amazed by ntfs-3g. It's not perfect, but it's an
impressive achievement.
