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Re: [Xen-users] snapshot backup at iscsi or dom0, which one is better?

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Subject: Re: [Xen-users] snapshot backup at iscsi or dom0, which one is better?
From: Simon Hobson <linux@xxxxxxxxxxxxxxxx>
Date: Sat, 15 Aug 2009 20:29:44 +0100
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Aclhk Aclhk wrote:
dom0 mounts disk from iscsi server lvm. domU mounts dom0 lvm.

pls kindly advise which one is better.

Neither can give you a clean backup - period. But beyond that, both will achieve the same effect - an image of a dirty disk that will need to be restored in it's entirety even if you only need on file from the backup.

Either way will give you an image of a dirty disk partition, missing anything in the guests cache waiting to be written. And that's also ignoring applications (particularly databases) that have dirty data in their own cache.

In short - imagine pulling the power cord. You backup will be the equivalent of what's on the disk at the point you kill the power.

If you want a usable and clean backup - do it from within the guest (so it will include any dirty cache) and don't forget applications like databases that typically have to be shut down, put into some sort of backup mode, or perform a data dump in order to get a clean backup.

Simon Hobson

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