On 28.09.2016 11:56, Kevin Wolf wrote:
> Am 28.09.2016 um 10:37 hat Denis V. Lunev geschrieben:
>> On 09/28/2016 11:34 AM, Kevin Wolf wrote:
>>> Am 27.09.2016 um 20:59 hat Denis V. Lunev geschrieben:
>>>> On 09/27/2016 08:04 PM, Paolo Bonzini wrote:
>>>>> On 27/09/2016 15:28, Denis V. Lunev wrote:
>>>>>> On 09/27/2016 03:07 PM, Paolo Bonzini wrote:
>>>>>>> ----- Original Message -----
>>>>>>>> From: "Denis V. Lunev" <[email protected]>
>>>>>>>> To: "Paolo Bonzini" <[email protected]>
>>>>>>>> Cc: "Vladimir Sementsov-Ogievskiy" <[email protected]>,
>>>>>>>> [email protected], [email protected],
>>>>>>>> [email protected], [email protected],
>>>>>>>> [email protected], [email protected], [email protected],
>>>>>>>> [email protected]
>>>>>>>> Sent: Tuesday, September 27, 2016 12:25:54 PM
>>>>>>>> Subject: Re: [PATCH] proto: add 'shift' extension.
>>>>>>>>
>>>>>>>> On 09/27/2016 01:15 PM, Paolo Bonzini wrote:
>>>>>>>>>> We could go in a different direction and export flag
>>>>>>>>>> 'has_zero_init' which will report that the storage is
>>>>>>>>>> initialized with all zeroes at the moment. In this
>>>>>>>>>> case mirroring code will not fall into this
>>>>>>>>>> branch.
>>>>>>>>> Why don't you add the zero_init flag to QEMU's NBD driver instead?
>>>>>>>> for all cases without knowing real backend on the server side?
>>>>>>>> I think this would be wrong.
>>>>>>> Add it to the command line, and leave it to libvirt or the user to
>>>>>>> pass "-drive file.driver=nbd,...,file.zero-init=on".
>>>>>> I have started with something very similar for 'drive-mirror' command.
>>>>>> We have added additional flag for this to improve migration speed
>>>>>> and this was rejected.
>>>>> You can add it through the filename path too, through a URI option
>>>>> "nbd://...?zero-init=on".
>>>>>
>>>>> Paolo
>>>> ha, cool idea! Thanks!
>>> What's the advantage of writing "?zero-init=on" instead of
>>> ",zero-init=on"? Doesn't it only add more string parsing code for no
>>> benefit?
>>>
>>> Kevin
>> Here I appreciate the idea to pass command line options in the
>> target file name. Will it be performed via comma or '?' - there
>> is no difference for us. We will check and use what is already
>> implemented.
>>
>> The most important for us is an approach.
> For me, too. With commas it's not part of the file name that must be
> parsed out of the string, but a separate option, which is the much
> cleaner approach.
>
> The good thing is that the conversion of NBD to individual options has
> progressed far enough that you wouldn't even be able to implement the
> URL extension without implementing the separate option, too. :-)
> (Because all the URL parser does is splitting the URL into individual
> options before passing them to nbd_open().)
>
> Kevin
Just note: we can use json instead of url, like this: virsh
qemu-monitor-command backup-vm
'{"execute":"drive-backup","arguments":{"device": "disk", "target":
"json://{\"driver\":\"nbd\",\"host\":\"127.0.0.1\",\"port\":\"10809\",\"zero-init\":\"on\"}",
"mode": "existing", "sync": "full"}}'
--
Best regards,
Vladimir
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