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From: | Anthony Liguori |
Subject: | [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes" |
Date: | Wed, 25 Aug 2010 08:37:45 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100713 Lightning/1.0b1 Thunderbird/3.0.6 |
On 08/25/2010 08:07 AM, Avi Kivity wrote:
The next allocation can then be filled from memory, so the allocation sync is amortized over many blocks. A power fail will leak the preallocated blocks, losing some megabytes of address space, but not real disk space.It's a clever idea, but it would lose real disk space which is probably not a huge issue.Not real disk space since no pwrite() would ever touch the disk. If the image were copied, _then_ we'd lose the disk space, if the copy command and filesystem don't optimize zeros away. \
Ok. Regards, Anthony Liguori
And that's it. There is no scenario where the disk is corrupted._if_ that's the only failure mode.If we had another disk format that only supported growth and metadata for a backing file, can you think of another failure scenario?I can't think of one, but that's not saying much.
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