Re: [Qemu-devel] [Bug 1458239] Re: Use qed instead of qcow2 for "-snapshot" functionality

[Paolo Bonzini <pbonzini@redhat.com>]

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On 26/05/2015 12:18, Stefan Hajnoczi wrote:
> On Sun, May 24, 2015 at 07:54:19AM -0000, Коренберг Марк wrote:
>> Sorry, I did not know tha qed is just experimental format. I
>> thought that qed is successor of qcow2. Can you add some links
>> that qcow is not worse than qed ? I did not make any benchmark,
>> just read some articles
> 
> Hi, QED's write performance optimization has been added to qcow2
> (-o lazy_refcounts=on).
> 
> qcow2 has been optimized further in the meantime and is the
> recommended image file format if raw lacks features that you need.

Also, -snapshots uses "cache=unsafe", so there should be no
performance difference between the two anyway.

Random idea: should qcow2 always use lazy refcounts if it receives
"cache=unsafe"?

Paolo
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