Re: thin provisioned LUN support

Ric Wheeler
2008-11-07T18:42:10Z

Theodore Tso wrote:
> On Fri, Nov 07, 2008 at 01:09:48PM -0500, Ric Wheeler wrote:
>
>> I don't think that trim bugs should be that common - we just have to be
>> very careful never to send down a trim for any uncommitted block.
>>
>>
>
> The trim code probably deserves a very aggressive unit test to make
> sure it works correctly, but yeah, we should be able to control any
> trim bugs.
>
>
>> Simple is always good, but I still think that the coalescing (even basic
>> coalescing) will be a critical performance feature.
>>
>
> Will we be able to query the device and find out its TRIM/UNMAP
> alignment requirements? There is also a balanace between performance
> (at least if the concern is sending too many separate TRIM commands)
> and giving the SSD more flexibility in its wear-leveling allocation
> decisions by sending TRIM commands sooner rather than later.
>
> - Ted
>

T10 is still working on the proposal for how to display unmap related
information for SCSI, so we don't even have a consistent way to find
this out today for this population.

Not sure what is possible for the ATA devices,

Ric