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Date:      Mon, 11 May 1998 23:31:34 -0700 (PDT)
From:      Tom <tom@uniserve.com>
To:        Tim Tsai <tim@futuresouth.com>
Cc:        am@f1.ru, Allen Smith <easmith@beatrice.rutgers.edu>, bofh@terranova.net, greg@uswest.net, freebsd-stable@FreeBSD.ORG
Subject:   Re: SCSI problems?
Message-ID:  <Pine.BSF.3.96.980511232027.9588E-100000@shell.uniserve.ca>
In-Reply-To: <19980512011910.06503@futuresouth.com>

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On Tue, 12 May 1998, Tim Tsai wrote:

> > On Tue, 12 May 1998, Tim Tsai wrote:
> > 
> > > > > > the AHC_ options in the kernel configuration file.
> > > > > 
> > > > > Aren't those for EISA, not PCI devices in the first place? That's what
> > > > > the comments in LINT seem to indicate. I've also got an 2940UW,
> > > > > without any AHC_ options, and it hasn't been causing any problems -
> > > > > then again, the machine hasn't been up and running very long.
> > 
> >   No, the AHC_ options are can be used for either, but some EISA adapters
> > can't do scb paging.
> 
>   Please quote me correctly.  This is the second time on this thread
> already that the above was attributed to me.  I didn't write it.

  I never attributed that to you.  It just one piece of misinformat that
no one tackled (at least a response was not listed here.  Due to the
quoting depth, it is pretty obvious that was someone else.

...
> >   Also, an ncr adapter will do tagged commands quite well, and will
> > _easily_ outperform the ahc driver with tagged commands off.  It is also
> > much less expensive.  So basically, if you must run the ahc driver without
> > tagged commands, you could have saved money and gotten better performance
> > by getting an NCR810 or NCR875 based adapter.  However, the ahc driver 
> > with functioning tagged commands and paging is pretty quick, and handles
> > lots of simultaneous io better than an ncr based card.
> 
>   Well, some of us foolishly followed the advice of the mailing list
> archives and bought the Adaptec's and are stuck with them for awhile.

  They do work ok.  The disks you connect to them make all the
difference though.  Never Adaptec cards seem to be getting more finicky
though.  Under heavy load, I only get ahc crashes only about every 30 to
45 days.  I'm try a DPT triple-channel controler in that machine, as I've
yet to see a DPT related problem.

> New purchases are Symbios' but we do still have a few Adaptec's.  Can't
> wait for CAM.  Note that CAM doesn't work with NCR810 yet, as far as I
> know.

  There are also the DPT cards.  Some do RAID, and some are RAID
upgradable via a daughtercard.

>   I think it's just part of working with FreeBSD.  At one time there were
> problems with NCR cards - now there are problems with Adaptec.  Same with

  I don't think there every a time there were NCR problems.  My memory on
ncr only goes back to 2.1.5 or so though.

> de0 cards, etc.  We have accepted this as a fact of life and try to work
> within the constraints.  Unfortunately we can't treat every problem as
> if we can just go out and buy new hardware and expect problems to disappear
> (or to not appear in the future).

  Problems should not appear in existing working hardware.  I certainly
don't see that here.  All the Adaptec cards that worked before, work now.
The de driver has been a pain, because an almost completely new driver was
imported, making some new cards work, and breaking some old cards.  The
new strategy seems to be to avoid touching the de driver because it seems
impossible not to break something that worked before.

>   Tim

Tom


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