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Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver
From: |
Dietmar Maurer |
Subject: |
Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver |
Date: |
Thu, 21 Feb 2013 08:42:01 +0000 |
> >> This should call bdrv_is_allocated_above like the other block jobs do.
> >> It would be needed later anyway to backup only the topmost image.
> >
> > I do not need that information now, so why do you want that I add dead code?
>
> I think you do. You're wasting time reading unallocated clusters and checking
> that they are zero. bdrv_is_allocated_above gives you the same information
> much more efficiently.
I thought that just returns information if the data is allocated, or if data
is on backing file?
Or is data guaranteed to be zero if bdrv_is_allocated_above() return 0?
> Do VMA files have to store all the blocks of the source file?
I only use it for full backups currently.
If you want incremental backups, you need to store information about the base
image,
and this is not the scope of this patch. IMHO incremental backup which
references to other
images are a mess. They are difficult to generate and difficult to maintain.
I would prefer to use some kind of Content Addressable Storage, using hashes.
That way you have advantages of full backups and incremental backups
(deduplication).
Having the additional advantage that we can easily rsync that data to another
site.
- [Qemu-devel] [PATCH v3 3/6] add backup related monitor commands, (continued)
- [Qemu-devel] [PATCH v3 3/6] add backup related monitor commands, Dietmar Maurer, 2013/02/19
- [Qemu-devel] [PATCH v3 6/6] add vm state to backups, Dietmar Maurer, 2013/02/19
- [Qemu-devel] [PATCH v3 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/19
- [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/19
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Eric Blake, 2013/02/19
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/20
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver,
Dietmar Maurer <=
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v3 2/6] add basic backup support to block driver, Paolo Bonzini, 2013/02/21
Re: [Qemu-devel] [PATCH v3 1/6] RFC: Efficient VM backup for qemu, Eric Blake, 2013/02/19
Re: [Qemu-devel] [PATCH v3 1/6] RFC: Efficient VM backup for qemu, Dietmar Maurer, 2013/02/20