Re: [PATCH v6 2/4] Add support for SCT Write Same

Shaun Tancheff
2016-08-22T22:07:52Z

On Mon, Aug 22, 2016 at 3:14 PM, Tom Yan <tom.ty89@gmail.com> wrote:
> On 23 August 2016 at 03:43, Shaun Tancheff <shaun.tancheff@seagate.com> wrote:
>>
>> Why would we enforce upper level limits on something that doesn't
>> have any?
>
> If we advertise a limit in our SATL, it makes sense that we should
> make sure the behaviour is consistent when we issue a write same
> through the block layer / ioctl and when we issue a SCSI Write Same
> command directly (e.g. with sg_write_same). IMHO that's pretty much
> why SBC would mandate such behaviour as well.

Breaking would be advertising a limit that is too high and failing.
Advertising a lower limit and succeeding may not be ideal for all
possible use cases, but it's not breaking behaviour.

>>
>> If the upper level, or SG_IO, chooses to set a timeout of 10 hours and
>> wipe a whole disk it should be free to do so.
>>
>
> That's why I said, "if you are going to advertise an Maximum Write Same Length".

--
Shaun Tancheff