[555] in linux-scsi channel archive
Re: Errors & Unit Attention
daemon@ATHENA.MIT.EDU (Stephen D. Williams)
Mon Aug 28 21:35:31 1995
From: sdw@lig.net (Stephen D. Williams)
To: bsa@kf8nh.wariat.org (Brandon S. Allbery KF8NH)
Date: Mon, 28 Aug 1995 10:22:26 -0400 (EDT)
Cc: sdw@lig.net, eric@aib.com, lnz@dandelion.com, linux-scsi@vger.rutgers.edu
In-Reply-To: <199508270314.XAA00527@kf8nh.wariat.org> from "Brandon S. Allbery KF8NH" at Aug 26, 95 11:14:05 pm
>
> In your message of Sat, 26 Aug 1995 15:32:13 EDT, you write:
> +-----
> | This is one of those areas that separates a good OS from a great one:
> |
> | SCSI can electrically and protocol wise handle hot connection and disconnecti
> on
> | of drives, but many OS's (if not most) don't retry operations sufficiently
> | to handle it.
> +-----
>
> Try it with a PC SCSI device sometime. AHA1542s in particular will freeze
> solid - the on-board microcode crashes and you have to reset/powerdown to
> get it back. (I have had it happen.) Most other PC SCSI cards of my
This is one of the reasons that I will NEVER use Adaptec again.
I've had it do this, and burn out the SCSI fuse, with attempted use
of 8mm tape drives...
I've had so much better results with Future Domain it's not even a contest...
(Note: most of my SCSI hacking/assembling days was in 8-bit/16-bit era...)
> acquaintance also fail rather poorly in such a situation. (And for the
> multi-architecture folks: you can destroy an SBus SCSI card by trying to
> hot-plug devices...)
Really? Shouldn't be, according to my dim memory of the standard.
I've also seen it done a lot.
> It hardly seems worth catering to a facility not supported by much if any
> hardware.
I disagree: one of the things that I'm slowly working on is RAID and
RAID like support built into the kernel and/or device drivers: having
a kernel that will support hot-swap gracefully and robustly as
possible is a must! (Assuming at least some hardware out there will
support it. One trick often used by the hot-swappable hardware is
simply to build connectors where either power or a reset line always
breaks first and makes last.)
> ++Brandon
> --
> Brandon S. Allbery Linux & Solaris 2 hack; ham; soccer nut; pipe smoker
> bsa@kf8nh.wariat.org APK Net Ltd. *is* The Internet in Northern Ohio
> bsa@telotech.com Telotech, Inc., custom Unix database solutions
>
>
--
Stephen D. Williams 25Feb1965 VW,OH (FBI ID) sdw@lig.net http://www.lig.net/sdw
Consultant, Vienna,VA Mar95- 703-918-1491W 43392 Wayside Cir.,Ashburn, VA 22011
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Pres.: Concinnous Consulting,Inc.;SDW Systems;Local Internet Gateway Co.;28May95
