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xen-users
Re: [Xen-users] A simple backup
Mark Williamson wrote:
When you take an atomic snapshot of a domU's state, it's much the same kind of
backup image as you'd get by yanking the power from a server, removing its
hard drive and copying it byte-for-byte - often readable but definitely not
clean. That consistency problem is what makes it impossible to guarantee
that such backups are definitely readable.
Hi Mark,
Some thoughts about your comment.
In our environment, one of the requirements for the OS and applications
is that it must be able to recover quickly and cleanly from a power
failure. This is actually one of the reasons why we're starting to
migrate some stuff to zfs : because, when used properly, it always
guarantee filesystem consistency in the event of power failure.
IMHO, even the best commercial SAN-based backup solution uses that
assumption, so for practical purposes, atomic backup for domU's storage
should be sufficient.
It would be nicer if you could somehow guarantee a
consistent filesystem state on your disk snapshot. I've been looking into
how to do this and I believe it's quite possible to modify the code to
support this properly.
It would be interesting if you can make it happen.
Regards,
Fajar
smime.p7s
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