On Mon, 2011-02-28 at 16:05 -0500, Ted Ts'o wrote:

On Mon, Feb 28, 2011 at 03:19:21PM -0500, Martin K. Petersen wrote:

quoted

Kind of, yes. But that involves teaching every ATA driver in $LEGACY_OS
about 4KB logical blocks. There is little value is switching to 4KB
logical blocks in the first place. So the claim is that it is easier to
stick with 512-byte addressing, leave the I/O stack intact, and require
the filesystem to always issue aligned units of 4KB.

That saves the drive vendors from implementing RMW logic and puts the
burden on us. Perfect deal.

So it there a reliable way to detect that disk drives that don't have
the Read-Modify-Write logic?  If that can be reflected up the I/O
layer I can have mke2fs enforce that restriction, which currently we
only enforce if the logical blocksize is 4k.

Well, we could blacklist it to force the logical block size up to 4k
based on identification by the inquiry strings (that, of course,
involves finding all the inquiry strings).  It's just that we're
practically out of blacklist bits ... it's just I thought we'd finally
got all manufacturers on the same page as standards compliance ... doing
something like this would send us back to the dark ages again.

Could we just have a campaign to send drives that fail like this back?
That might actually get the message across to the manufacturers .. and
it could arguably be covered under the warranty.

James