Re: thin provisioned LUN support

James Bottomley
2008-11-06T16:21:13Z

On Thu, 2008-11-06 at 10:57 -0500, jim owens wrote:
> James Bottomley wrote:
>
> > By the way, the latest (from 2 days ago) version of the Thin
> > Provisioning proposal is here:
> >
> > http://www.t10.org/ftp/t10/document.08/08-149r4.pdf
>
> If I understand the spec [ not likely ;) ] ...
>
> jim owens wrote:
>
> > And the vendors need to provide the device trim chunk size in
> > a standard way (like scsi geometry) to the filesystem.
>
> It may be that the READ CAPACITY (16) provides the trim chunk
> size via the "logical blocks per physical block exponent".
>
> But since this is just a T10 spec, I would want that
> interpretation verified by the array vendors.

This could be ... I think it's original intention was to allow us to
figure out that we had a 4k sector disk emulating a 512b sector one.
However, it's also a useful way to parametrise the erase block size for
SSDs as well as the array track size.

James