[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd |
Date: |
Fri, 19 Jul 2013 10:20:10 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 19.07.2013 um 08:29 hat Wenchao Xia geschrieben:
> δΊ 2013-7-17 22:23, Eric Blake ει:
> >On 07/17/2013 08:03 AM, Wenchao Xia wrote:
> >>This series allow user to read internal snapshot's contents without qemu-img
> >>convert. Another purpose is that, when qemu is online and have taken an
> >>internal snapshot, let user invoke qemu-nbd to do any thing on it except
> >>write.
> >>
> >>This brings two interesting issues:
> >>1 is it safe to let qemu-nbd and qemu access that file at same time?
> >
> >Probably not, for the same reason we tell people to not use qemu-img
> >while qemu is active on a file.
> >
> For external case, or backing chain, qemu-nbd export while qemu is
> active, do you think it is OK?
>
> base->imageA
>
> qemu-nbd export base
> qemu use imageA.
It depends. If you use 'qemu-nbd -r' to export it, it's okay. The
reason is that it's allowed to have either one process opening the file
read-write, or an arbitrary number of processes opening the file
read-only. In the case of qemu using imageA, base is only opened
read-only, so qemu-nbd can be another read-only user.
Kevin
- [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd, Wenchao Xia, 2013/07/17
- [Qemu-devel] [PATCH 3/4] qemu-nbd: add doc for internal snapshot export, Wenchao Xia, 2013/07/17
- [Qemu-devel] [PATCH 1/4] snapshot: distinguish id and name in load_tmp, Wenchao Xia, 2013/07/17
- [Qemu-devel] [PATCH 2/4] qemu-nbd: support internal snapshot export, Wenchao Xia, 2013/07/17
- [Qemu-devel] [PATCH 4/4] qemu-iotests: add 057 internal snapshot export with qemu-nbd case, Wenchao Xia, 2013/07/17
- Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd, Eric Blake, 2013/07/17
- Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd, Wenchao Xia, 2013/07/19
- Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd,
Kevin Wolf <=
- Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd, Wenchao Xia, 2013/07/22
- Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd, Stefan Hajnoczi, 2013/07/18
Re: [Qemu-devel] [PATCH 0/4] export internal snapshot by qemu-nbd, Wenchao Xia, 2013/07/24