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Date: Fri, 10 Sep 2010 17:06:49 +0300
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] [RFC] qed: Add QEMU Enhanced Disk format
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, qemu-devel@nongnu.org

  On 09/10/2010 04:16 PM, Anthony Liguori wrote:
>> btw, despite being not properly designed, qcow2 is able to support 
>> TRIM.  qed isn't able to, except by leaking clusters on shutdown.  
>> TRIM support is required unless you're okay with the image growing 
>> until it is no longer sparse (the lack of TRIM support in guests make 
>> sparse image formats somewhat of a joke, but nobody seems to notice).
>
>
> It's actually pretty easy in QED and it should perform very well.
>
> http://wiki.qemu.org/Features/QED/Trim
>

If you don't add a free list, this is a pretty bad implementation.  If 
you do, you're back to qcow2's problems.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.