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Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command
From: |
Dietmar Maurer |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command |
Date: |
Tue, 21 May 2013 10:58:47 +0000 |
> >> True, but that would happen only in case the host crashes. Even for
> >> a QEMU crash the changes would be safe, I think. They would be
> >> written back when the persistent dirty bitmap's mmap() area is
> >> unmapped, during process exit.
> >
> > I'd err on the side of caution, mark the persistent dirty bitmap while
> > QEMU is running. Discard the file if there was a power failure.
>
> Agreed. Though this is something that management must do manually, isn't it?
> QEMU cannot distinguish a SIGKILL from a power failure, while management
> can afford treating SIGKILL as a power failure.
>
> > It really depends what the dirty bitmap users are doing. It could be
> > okay to have a tiny chance of missing a modification but it might not.
I just want to mention that there is another way to do incremental backups.
Instead
of using a dirty bitmap, you can compare the content, usually using a digest
(SHA1) on clusters.
That way you can also implement async replication to a remote site (like MS do).
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, (continued)
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Paolo Bonzini, 2013/05/17
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Stefan Hajnoczi, 2013/05/20
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Paolo Bonzini, 2013/05/20
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Stefan Hajnoczi, 2013/05/21
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Paolo Bonzini, 2013/05/21
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Stefan Hajnoczi, 2013/05/21
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Paolo Bonzini, 2013/05/21
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command,
Dietmar Maurer <=
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Stefan Hajnoczi, 2013/05/22
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Dietmar Maurer, 2013/05/22
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Dietmar Maurer, 2013/05/22
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Stefan Hajnoczi, 2013/05/23
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Dietmar Maurer, 2013/05/23
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Stefan Hajnoczi, 2013/05/24
- Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup command, Dietmar Maurer, 2013/05/24