Re: [PATCH] blacklist NCQ on Seagate Barracuda ST380817AS

[Mark Lord]

Jeff Garzik wrote:
> Paolo Ornati wrote:
> > On Sun, 30 Sep 2007 15:29:08 +0100
> > Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > > > Seagate Barracuda ST380817AS has troubles with NCQ. For example,
> > > > unpacking a tarball on an XFS filesystem gives this:
> > > >
> > > > ata1.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x2 frozen
> > > > ata1.00: cmd 61/40:00:29:a3:98/00:00:00:00:00/40 tag 0 cdb 0x0 data 
> > > > 32768 out
> > > >          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)  
> > > What makes you sure that is an NCQ problem ?
> >
> > It goes away with:
> > echo 1 > /sys/block/sda/device/queue_depth
> >
> > I have this problem only with XFS, and even with XFS it goes away
> > mounting with "nobarrier"...
>
> This last is an interesting datapoint.
>
> I wonder if libata has a generic problem with NCQ + FLUSH CACHE.

Yeah, that's pretty suspicious.  Prior to issuing a FLUSH_CACHE op,
one must first drain all outstanding NCQ commands (and not issue new ones).

I'm sure the code must *try* to do that, but perhaps there's a bug in there?
Or just another drive bug?

??
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