On 24.09.2016 16:42, Vladimir Sementsov-Ogievskiy wrote:
> On 24.09.2016 15:06, Vladimir Sementsov-Ogievskiy wrote:
>> On 24.09.2016 00:21, Wouter Verhelst wrote:
>>> On Fri, Sep 23, 2016 at 02:00:06PM -0500, Eric Blake wrote:
>>>> My preference would be a new flag to the existing commands, with
>>>> explicit documentation that 0 offset and 0 length must be used with
>>>> that
>>>> flag, when requesting a full-device wipe.
>>> Alternatively, what about a flag that says "if you use this flag, the
>>> size should be left-shifted by X bits before processing"? That allows
>>> you to do TRIM or WRITE_ZEROES on much larger chunks, without being
>>> limited to "whole disk" commands. We should probably make it an illegal
>>> flag for any command that actually sends data over the wire, though.
>>>
>>
>>
>> Note: if disk size is not aligned to X we will have to send request
>> larger than the disk size to clear the whole disk.
>
> which is not beautiful.. And splitting the request into two:
> (disk_size / X * X) and (disk_size % X) is not beautiful too. May be
> flag, that says 'whole disk request' is more appropriate? Nothing
> prevents adding then flag about X-shift.
>
>
Also, accordingly to documentation, NBD_CMD_TRIM is not appropriate for
disk clearing:
* `NBD_CMD_TRIM` (4)
A hint to the server that the data defined by len and offset is no
longer needed. A server MAY discard len bytes starting at offset, but
is not required to.
After issuing this command, a client MUST NOT make any assumptions
about the contents of the export affected by this command, until
overwriting it again with `NBD_CMD_WRITE`.
- it may do nothing.. So, what to do with this? add flag FORCE_TRIM for
this command? Or add FORCE_HOLES flag to WRITE_ZEROES?
--
Best regards,
Vladimir
------------------------------------------------------------------------------
_______________________________________________
Nbd-general mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/nbd-general
