Re: Any objections/comments on axing out old ATA stack?

From: Alexander Motin <mav_at_FreeBSD.org>
Date: Sun, 21 Apr 2013 14:59:59 +0300
ATA controller drivers are delaying conflicting commands, avoiding
conflicts in device.
21.04.2013 14:32 пользователь "Jeremy Chadwick" <jdc_at_koitsu.org> написал:

> On Sun, Apr 21, 2013 at 02:11:04PM +0300, Alexander Motin wrote:
> > On 21.04.2013 00:29, Jeremy Chadwick wrote:
> > >- The ATA commands which lead up to the error also vary.  Many are for
> > >   write requests, and from some entries I can see that the OS was doing
> > >   NCQ writes (WRITE FPDMA QUEUED) and then suddenly decided to do a
> > >   classic 28-bit LBA write (WRITE DMA).  I'm not sure why an OS would
> do
> > >   this (there's nothing optimal about it) unless there were conditions
> > >   occurring where the OS/ATA driver said "this NCQ write isn't working
> > >   (timeout, etc.), let me retry with a classic 28-bit LBA write".
> >
> > ATA disk driver in CAM inserts non-queued command every several
> > seconds of continuous load to limit possible command starvation
> > inside the disk. SCSI driver does alike things, but inserts ordered
> > command flag, that does not exist in SATA, instead of different
> > command.
>
> Thanks for the insights Alexander, greatly appreciated.
>
> I'm a little confused by your description, because if I'm reading it
> right, it sounds like it conflicts with what the ACS-2 spec states.
> Quoting T13/2015-D rev 3 (I'm aware it's a working draft), section
> 4.16.1:
>
> "If the device receives a command that is not an NCQ command while NCQ
> commands are in the queue, then the device shall return command aborted
> for the new command and for all of the NCQ commands that are in the
> queue."
>
> I assume this means ABRT status is returned to the host controller; if
> so (and by design of course), how do we differentiate between that
> condition and any other I/O condition that induces ABRT?
>
> Possibly in the answer is in this admission: I should probably get
> around to reading ATA8-AST sometime.  :-)
>
> --
> | Jeremy Chadwick                                   jdc_at_koitsu.org |
> | UNIX Systems Administrator                http://jdc.koitsu.org/ |
> | Mountain View, CA, US                                            |
> | Making life hard for others since 1977.             PGP 4BD6C0CB |
>
Received on Sun Apr 21 2013 - 10:00:00 UTC

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