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Re: [Qemu-devel] QCow v2
From: |
Christian MICHON |
Subject: |
Re: [Qemu-devel] QCow v2 |
Date: |
Tue, 11 Jul 2006 13:30:18 +0200 |
ok, I did this experiment (long and painful).
a XP2003/SP1 qemu guest required 964,231,168 bytes qcow image.
zlib qcow image became 459,686,368 bytes.
lzma estimation (4k clusters) is 437,038,838 bytes.
Yes, 5% are still gained, but the time to get the lzma'ed qcow is
disastrous (especially on systems with anti-virus and anti-malware).
Do you still think it's worth it ?
On 7/4/06, Natalia Portillo <address@hidden> wrote:
Just there is a question:
If improvement is 5%, IS NOT THE SAME with a 5Mb HDD that with a 5Gb
HDD.
Wanna do testing with more real scenarios?
Like a Windows XP full installation for example?
I'm very sure that there will be a real difference.
Regards
El 04/07/2006, a las 15:51, Christian MICHON escribió:
> for what it's worth:
> qcow with "lzo -9" would become 4155352 bytes (bigger than original
> zlib qcow).
>
> yet it's true at the compression and decompression stages that it
> feels faster...
>
> On 7/4/06, Elefterios Stamatogiannakis <address@hidden>
> wrote:
>> I agree
>>
>> Lzma and zlib are pretty much equivalent, so there is pretty much
>> nothing to be gained except slightly more compression.
>>
>> On the other hand with lzo (1) there would be quite a considerable
>> speed
>> improvement at the cost of compression.
>>
>> It could also mean that reading on the qcow format could some
>> times be
>> faster (with compressible data) than reading directly from the
>> hard disk.
>>
>> lefteris
>>
>> (1) http://www.oberhumer.com/opensource/lzo/
>>
>> Johannes Schindelin wrote:
>> > Hi,
>> >
>> > On Tue, 4 Jul 2006, Christian MICHON wrote:
>> >
>> >> how about also adding lzma compression for qcow ?
>> >
>> > Why lzma? We already have a dependency on zlib, why not just
>> take that?
>> >
>> > Ciao,
>> > Dscho
>> >
>> >
>> > _______________________________________________
>> > Qemu-devel mailing list
>> > address@hidden
>> > http://lists.nongnu.org/mailman/listinfo/qemu-devel
>>
>>
>> _______________________________________________
>> Qemu-devel mailing list
>> address@hidden
>> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>>
>
>
> --
> Christian
>
>
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> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>
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Christian
- [Qemu-devel] QCow v2, Nathaniel McCallum, 2006/07/03
- Re: [Qemu-devel] QCow v2, Johannes Schindelin, 2006/07/04
- Re: [Qemu-devel] QCow v2, Raphaël Rigo, 2006/07/04
- Re: [Qemu-devel] QCow v2, Fabrice Bellard, 2006/07/04
- Re: [Qemu-devel] QCow v2, Christian MICHON, 2006/07/04
- Re: [Qemu-devel] QCow v2, Johannes Schindelin, 2006/07/04
- Re: [Qemu-devel] QCow v2, Elefterios Stamatogiannakis, 2006/07/04
- Re: [Qemu-devel] QCow v2, Christian MICHON, 2006/07/04
- Re: [Qemu-devel] QCow v2, Natalia Portillo, 2006/07/04
- Re: [Qemu-devel] QCow v2,
Christian MICHON <=
- Re: [Qemu-devel] QCow v2, André Braga, 2006/07/11
- Re: [Qemu-devel] QCow v2, Christian MICHON, 2006/07/04
- Re: [Qemu-devel] QCow v2, Fabrice Bellard, 2006/07/04
- Re: [Qemu-devel] QCow v2, Christian MICHON, 2006/07/04
- Re: [Qemu-devel] QCow v2, Fabrice Bellard, 2006/07/04
- Re: [Qemu-devel] QCow v2, Christian MICHON, 2006/07/04
- Re: [Qemu-devel] QCow v2, Christian MICHON, 2006/07/04
- Re: [Qemu-devel] QCow v2, Johannes Schindelin, 2006/07/04
- Re: [Qemu-devel] QCow v2, Fabrice Bellard, 2006/07/04
- Re: [Qemu-devel] QCow v2, Julian Seward, 2006/07/04