[illumos-Developer] Changing sd_io_time to 8?

[Garrett D'Amore]

On Tue, 2011-05-03 at 08:41 -0700, Dmitry Yusupov wrote:
> 
> > -----Original Message-----
> > From: Deano [mailto:deano at rattie.demon.co.uk]
> > Sent: Tuesday, May 03, 2011 8:36 AM
> > To: 'Garrett D'Amore'; 'Joerg Schilling'
> > Cc: developer at lists.illumos.org
> > Subject: Re: [illumos-Developer] Changing sd_io_time to 8?
> > 
> > > Yes, but the SCSI commands and the support logic you need for cdroms
> > > are quite different from what you need for disks, even though there is
> > > a large area of overlap.  There's a reason that these are specified by
> > > different parts of the SCSI standards. :-)
> > >
> > >	- Garrett
> > 
> > 
> > I agree with Garrett, the sd driver has to deal with
> > 
> > SCSI drives
> > SCSI removable
> > SAS
> > ATA
> > SATA
> > ATAPI
> > (and I expect a few more I've forgotten)
> > 
> > It’s a bit nasty for one driver to have to deal with that lot, given the number
> > of sub-standards and appendums (and bugs!) each protocol has generated
> > over the years.
> 
> I wonder if we enhance blkdev driver with SCSI handling, can we clean this up over time?

NO NO NO.

That way lies madness, on many fronts.

The whole *point* of blkdev is to stop trying to do SCSI for devices
that have nothing to do with SCSI.

Also, cleaning up the current mess would break a lot of things, as paths
to filesystems, etc. are all dependent on the drivers.  It would require
significant effort to change the current mess without breaking
compatibility.

	- Garrett

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