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Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format
From: |
Dietmar Maurer |
Subject: |
Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format |
Date: |
Fri, 22 Feb 2013 13:11:52 +0000 |
> > We currently only need 8 bytes per cluster, which results in small files.
>
> So how big is the metadata overhead? If you always copy 64k at once (which is
> a
> very conservative assumption - at least for the background copy you'll have
> much larger blocks), then an 8 byte header for each is 0.01%. Increasing that
> to
> 0.02% doesn't sound like a huge problem to me.
We do not always write 64K, because we omit regions filled with zeroes.
So the picture gets a bit worse when you have sparse images.
For example, if you backup a file which mostly contains empty blocks,
you will duplicate the size of the resulting file!
And this is a very common case.
Opposed to that, VM images >= 1Petabyte are very uncommon.
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, (continued)
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Eric Blake, 2013/02/20
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Kevin Wolf, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Eric Blake, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Stefan Hajnoczi, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Kevin Wolf, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format,
Dietmar Maurer <=
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Kevin Wolf, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Kevin Wolf, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Kevin Wolf, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 4/6] introduce new vma archive format, Kevin Wolf, 2013/02/22