RE: thin provisioned LUN support

Black_David
2008-11-10T02:36:10Z

Ted,

> On Fri, Nov 07, 2008 at 01:41:35PM -0500, Ric Wheeler wrote:
> >> Will we be able to query the device and find out its TRIM/UNMAP
> >> alignment requirements? There is also a balance 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.
> >>
> > 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.
>
> Yeah, I know, the rhetorical question was mostly addressed at David
> Black. :-)

Well, here's a real answer ... that should be coming in T10/08-149r5 as
an addition to the block device limits VPD page. Sorry for the delay
- I probably ought to remind Ric not to start this sort of discussion
*during* the T10 meetings - in contrast to the kernel, my brain is far
less effective at multi-tasking ;-).

FYI,
--David