From: Paolo Bonzini <pbonzini@redhat.com>
To: Kuniyasu Suzaki <k.suzaki@aist.go.jp>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] delvm does not reduce the qcow2 file size
Date: Tue, 16 Oct 2012 13:19:42 +0200 [thread overview]
Message-ID: <507D42CE.1030107@redhat.com> (raw)
In-Reply-To: <20121016.200633.61119037.k.suzaki@aist.go.jp>
Il 16/10/2012 13:06, Kuniyasu Suzaki ha scritto:
>>>> QEMU should also convert the unused clusters to "holes" in the file
>>>> > >> system, but it doesn't do that yet.
>>> > >
>>> > > I hope a qcow2 file is reduced automatically when a snapshot is deleted.
>> >
>> > Yes, that's part of the plan. The file would not reduce its size, but
>> > the space would still be given back to the filesystem.
> Do you plan to use a space file system?
Any file system that support holes, including ext2/3/4 or btrfs or XFS,
would actually reclaim the space.
> Is it difficult to reduce a qcow2 file when a snapshot is deleted?
There is no guarantee that no data was allocated after the snapshot. If
it was, it is not possible to reduce the qcow2 file's size without
implementing some kind of "defragmentation".
Paolo
prev parent reply other threads:[~2012-10-16 11:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-15 9:33 [Qemu-devel] delvm does not reduce the qcow2 file size Kuniyasu Suzaki
2012-10-15 13:25 ` Paolo Bonzini
2012-10-15 14:24 ` Kevin Wolf
2012-10-16 6:23 ` Kuniyasu Suzaki
2012-10-16 6:54 ` Paolo Bonzini
2012-10-16 11:06 ` Kuniyasu Suzaki
2012-10-16 11:19 ` Paolo Bonzini [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=507D42CE.1030107@redhat.com \
--to=pbonzini@redhat.com \
--cc=k.suzaki@aist.go.jp \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).