Re: [Qemu-devel] drive transactions (was Re: [PATCH 2/2 v2] Add the blockdev-reopen and blockdev-migrate commands)

[Paolo Bonzini]

On 02/27/2012 03:59 PM, Anthony Liguori wrote:
> The problem is that the current commands are not designed well.  For
> instance, multi-snapshot could look like:
> 
> block-freeze ide0-hd0
> block-freeze ide1-hd1
> block-reopen ide0-hd0 my-new-file0.qcow2
> block-reopen ide1-hd1 my-new-file1.qcow2
> block-unfreeze ide1-hd1
> block-unfreeze ide1-hd0
> 
> This would work regardless of whether the commands were implemented
> asynchronously within QEMU too.

This looks good, too.  Positive: maps well to fsfreeze/thaw with help
from the guest agent.  Negative: you have to specify the devices three
times.  Overall, I think I like it.

However, you need to add freeze/unfreeze capabilities to the block
layer.  Not hard, but one more thing to do.

Paolo