Matthew Wilcox wrote:
On Mon, Nov 10, 2008 at 12:05:57PM -0500, Black_David@xxxxxxx wrote:
On Mon, 2008-11-10 at 19:31 +1100, Dave Chinner wrote:
I think this is the crux of the issue. IMO, it's not much of a
standard
when the spirit of the standard is to allow everyone to implement
different, non-deterministic behaviour....
I disagree. The discard request is a _hint_ from the upper layers, and
the storage device can act on that hint as it sees fit. There's
nothing
wrong with that; it doesn't make it "not much of a standard".
Bingo! That is exactly the spirit and thinking behind the UNMAP
proposal.
While that may be, it's hardly the spirit that Ric (at least) has been
promoting with dire warnings about how 'Enterprise class' customers will
react if Linux does the wrong thing for EMC arrays with discard/trim/unmap.
It would be nice to have arrays that can handle an OS that gives it
perfect information (as our current code should do) regardless of
alignment and size of requests.
Would something else be good enough is a reasonable question, but I fear
lots of disgruntled customers ;-)
ric
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