[pve-devel] [PATCH] qemu-img convert : use default cache=unsafe instead writeback

[Dominik Csapak]

ok nevermind then

On 08/01/2016 09:44 AM, Alexandre DERUMIER wrote:
>>> Answering myself, 'close' does not issue flush/fsync.
>
> close send a flush
>
> block.c
>
> static void bdrv_close(BlockDriverState *bs)
> {
>     BdrvAioNotifier *ban, *ban_next;
>
>     assert(!bs->job);
>
>     /* Disable I/O limits and drain all pending throttled requests */
>     if (bs->throttle_state) {
>         bdrv_io_limits_disable(bs);
>     }
>
>     bdrv_drained_begin(bs); /* complete I/O */
>     bdrv_flush(bs);
>
>
>
> It's was introduce by this commit
>
> [Qemu-devel] [PATCH v3] qemu-img: let 'qemu-img convert' flush data
> https://lists.nongnu.org/archive/html/qemu-devel/2012-04/msg02936.html
>
>
>
> ----- Mail original -----
> De: "dietmar" <dietmar at proxmox.com>
> À: "Dominik Csapak" <d.csapak at proxmox.com>, "pve-devel" <pve-devel at pve.proxmox.com>
> Envoyé: Lundi 1 Août 2016 09:37:20
> Objet: Re: [pve-devel] [PATCH] qemu-img convert : use default cache=unsafe instead writeback
>
>>> is this really safe?
>>>
>>> this also impacts cloning and the "move disk" function.
>>> what if i clone a vm to an nfs share and immediately move the vm to
>>> another host, then start it?
>>
>> I guess qemu-img does a flush before closing (or flush is automatic on
>> close?)?
>
> Answering myself, 'close' does not issue flush/fsync. So I wonder if qemu-img
> issue a flush?
>
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