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Re: [Qemu-block] [Qemu-devel] [PATCH] mirror: prevent 'top' mode mirrori
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From: |
Eric Blake |
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Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH] mirror: prevent 'top' mode mirroring when no backing file specified on the destination |
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Date: |
Mon, 19 Dec 2016 09:31:24 -0600 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 |
On 12/19/2016 04:38 PM, sochin jiang wrote:
> Mirroring using 'top' mode without backing file specified on the target can
> be success,
> but end with a disaster.
>
> For example:
> Migration can be success in this situation while the virtual machine on
> the destination
> is no longer usable because of backing lost.
>
I think this is a premature policy decision. Even though the user can
abuse it to lose data, I think there is still enough technical reason
for why a user might have a valid use case for doing this (perhaps for
creating incremental backups, where the user plans on re-chaining data
back together using 'qemu-img rebase -u'), so I don't think we should
forbid it at the qemu level.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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