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Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format |
Date: |
Wed, 08 Sep 2010 09:48:13 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100720 Fedora/3.0.6-1.fc12 Thunderbird/3.0.6 |
Am 07.09.2010 22:41, schrieb Anthony Liguori:
> There's two types of snapshots that I think can cause confusion.
> There's CPU/device state snapshots and then there's a block device snapshot.
>
> qcow2 and qed both support block device snapshots. qed only supports
> external snapshots (via backing_file) whereas qcow2 supports external
> and internal snapshots. The internal snapshots are the source of an
> incredible amount of complexity in the format.
>
> qcow2 can also store CPU/device state snapshots and correlate them to
> block device snapshots (within a single block device). It only supports
> doing non-live CPU/device state snapshots.
Which is not a property of the format, but of the implementation. I
think it shouldn't be too hard to introduce live snapshots.
> OTOH, qemu can support live snapshotting via live migration. Today, it
> can be used to snapshot CPU/device state to a file on the filesystem
> with minimum downtime.
>
> Combined with an external block snapshot and correlating data, this
> could be used to implement a single "snapshot" command that would behave
> like savevm but would not pause a guest's execution.
We'd need fields for referencing a VM state file from a QED image, just
like it's already done for backing files.
Kevin
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, (continued)
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Stefan Hajnoczi, 2010/09/08
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Avi Kivity, 2010/09/09
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Anthony Liguori, 2010/09/09
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Christoph Hellwig, 2010/09/09
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Avi Kivity, 2010/09/10
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Stefan Hajnoczi, 2010/09/10
- Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Avi Kivity, 2010/09/10
Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Avi Kivity, 2010/09/07
Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Blue Swirl, 2010/09/07
[Qemu-devel] Re: [RFC] qed: Add QEMU Enhanced Disk format, Michael S. Tsirkin, 2010/09/15
Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format, Khoa Huynh, 2010/09/16