Re: [PATCH 0/3] scsi: Add Hyper-V logical block provisioning quirks

From: James Bottomley
Date: Sat Oct 11 2014 - 13:42:03 EST

On Sat, 2014-10-11 at 10:39 -0700, Christoph Hellwig wrote:
> On Fri, Oct 10, 2014 at 08:49:01AM +0100, Sitsofe Wheeler wrote:
> > Microsoft Hyper-V virtual disks currently only claim SPC-2 compliance
> > even though they implement post SPC-2 features (such as thin
> > provisioning) which means the Linux kernel does not go on to test for
> > those features even though they are advertised.
> >
> > A previous patch attempted to add a quirk to workaround this but the
> > quirk was only enabled after the features had been scanned for, wouldn't
> > work for "small" disks and would quirk on all Hyper-V SCSI devices
> > (e.g. passthrough disks).
> >
> > The new patches partially revert the previous effort, add the quirk in a
> > more traditional manner to only Hyper-V virtual disks and work on small
> > virtual disks.
> This seems like might want a quirk to simply "force" a SPC3 compliance
> level?

This was initially suggested, but rejected by Microsoft because of other
problems advertising SPC-3 compliance brings. Perhaps the hyper-v
emulator has matured sufficiently that it will now work OK?


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