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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: |
Fri, 24 May 2013 09:53:02 +0000 |
> Maybe the best approach is to maintain a dirty bitmap while the guest is
> running, which is fairly cheap. Then you can use the dirty bitmap to only
> hash
> modified clusters when building the Merkle tree - this avoids reading the
> entire disk image.
Yes, this is an good optimization.
> > > I still think it's a cool idea. Making it work well will require a
> > > lot more effort than a dirty bitmap.
> >
> > How do you re-generate a dirty bitmap after a server crash?
>
> The dirty bitmap is invalid after crash. A full backup is required, all
> clusters
> are considered dirty.
>
> The simplest way to implement this is to mark the persistent bitmap "invalid"
> upon the first guest write. When QEMU is terminated cleanly, flush all dirty
> bitmap updates to disk and then mark the file "valid"
> again. If QEMU finds the file is "invalid" on startup, start from scratch.
Or you can compared the hash keys in that case?
Although I guess computing all those SHA1 checksums needs a considerable amount
of CPU time.
- 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, 2013/05/21
- 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, 2013/05/21
- 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 <=