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Re: [Qemu-block] dirty bitmap restore procedure
From: |
Kashyap Chamarthy |
Subject: |
Re: [Qemu-block] dirty bitmap restore procedure |
Date: |
Tue, 29 Nov 2016 18:50:11 +0100 |
User-agent: |
Mutt/1.6.0.1 (2016-04-01) |
On Tue, Nov 29, 2016 at 11:52:49AM -0500, John Snow wrote:
>
> On 11/29/2016 09:13 AM, Michael Ablassmeier wrote:
> > hi there,
[...]
> The problem here is that the bitmap you are creating is not synchronized to
> the backup you've just made. What if some writes have happened since you
> created your snapshot?
>
> You need to create your snapshot and add (or reset) the bitmap using a
> transaction.
Oh, good point, revisiting my old tests, I now recall using QMP
'trasaction' to address the point.
Perhaps you might already be aware, a quick example of transactions w/
QMP. Assuming you have '-qmp unix:./qmp-sock,server'
----------
./qmp-shell -v -p /export/qmp-sock
Welcome to the QMP low-level shell!
Connected to QEMU 2.5.50
(QEMU) transaction(
TRANS> blockdev-snapshot-sync device=drive-ide0-0-0
snapshot-file=overlay1.qcow2
TRANS> block-dirty-bitmap-add node=drive-ide0-0-0 name=bitmap0
TRANS> )
{
"execute": "transaction",
"arguments": {
"actions": [
{
"data": {
"device": "drive-ide0-0-0",
"snapshot-file": "overlay1.qcow2"
},
"type": "blockdev-snapshot-sync"
},
{
"data": {
"node": "drive-ide0-0-0",
"name": "bitmap0"
},
"type": "block-dirty-bitmap-add"
}
]
}
}
{
"return": {}
}
(QEMU)
----------
[Snip some detailed discussion.]
--
/kashyap