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Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation
From: |
Alberto Garcia |
Subject: |
Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation |
Date: |
Thu, 13 Apr 2017 11:05:49 +0200 |
User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Thu 13 Apr 2017 11:02:10 AM CEST, Kevin Wolf <address@hidden> wrote:
> I think you still need it if you don't want to look at the refcount
> blocks for every write. When you take an internal snapshot, you just
> increase the refcount of the L2 tables at first and keep the contents
> the same, including the subcluster information. On the first write to
> the cluster, like with normal images you need to copy the whole
> cluster, and whether this is the case is determined with the COPIED
> flag. (The copy can actually keep unallocated/zeroed subclusters that
> way, but data has to be copied for the whole cluster.)
>
> Of course, in all cases the COPIED flag is just an optimisation
> because it's always possible to look at the refcount blocks, but I
> don't think there is any difference between subclustered and
> traditional images in this respect.
Exactly :)
Berto
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, (continued)
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Kevin Wolf, 2017/04/10
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Alberto Garcia, 2017/04/11
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Max Reitz, 2017/04/11
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Alberto Garcia, 2017/04/11
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Eric Blake, 2017/04/11
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Alberto Garcia, 2017/04/12
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Max Reitz, 2017/04/12
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Alberto Garcia, 2017/04/13
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Kevin Wolf, 2017/04/13
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation,
Alberto Garcia <=
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Kevin Wolf, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Eric Blake, 2017/04/11
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Max Reitz, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Eric Blake, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Max Reitz, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Kevin Wolf, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Max Reitz, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Eric Blake, 2017/04/11
- Re: [Qemu-block] [Qemu-devel] [RFC] Proposed qcow2 extension: subcluster allocation, Max Reitz, 2017/04/11
- Re: [Qemu-block] [RFC] Proposed qcow2 extension: subcluster allocation, Alberto Garcia, 2017/04/12