From: devil@HellNet.org (Gil Tene)
Newsgroups: comp.sys.sun.admin,comp.sys.sun.hardware,comp.unix.solaris
Subject: SUMMARY : SCSI drives that work with Solaris 2.1
Date: 11 Jan 93 10:20:39 GMT
Followup-To: comp.sys.sun.admin
Organization: Diablery, cloud seven, Hell. (also 10A Inc.)

This is a summary of my findings (so far) on the subject of
SCSI drives that work under Solaris 2.1. It contains a workaround 
for drives that have problems with Solaris 2.1's new tag queuing 
feature.

Drives that have been confirmed to work with Solaris 2.1 
right off the bat :

Conner CP-3540.
Imprimis (CDC) 94181-702 (aka Wren 5).
IBM 1004Mb formatted 3.5" drive (in Acropolis ASI-1.0GIBM).
Seagate Elite 1.3GB
DEC DSP3105
Fujitsu M2624SA
Fujitsu 1.2GB 5.25" drive (M2266SA, I think).
Fujitsu M2263SA
Maxtor 660MB (no model number given).
HP 1.2GB and 660MB 5.25" disks (no model numbers given).
All Sun-supplied drives (of course).

Drives with known problems :

Toshiba MK-538FB, 1.2GB formatted.

I would like to receive data confirming more working drives 
under Solaris 2.1 (and ones that have problems, too). I will 
expand this summary as more data comes in a re-post.

*****************************************************************
Workaround for drives that have problems with tag queuing under
Solaris 2.1 :
*****************************************************************

I have personally undergone this with the Toshiba 1.2GB formatted
(MK-538FB) drive. And I have it working now. Let me start with a bit 
of background and symptoms description :

To begin with, Solaris 2.1 added the use of tag queuing on SCSI
disks. Tag queuing allows the OS to send more than one request
at a time to the disk, tagging each request. The drive can then
handle the requests can then be handled in optimal order by the
drive, and the OS distinguishes the requests according to their 
tag (not their order). This feature is useful in multithreaded 
systems, and gives a potential performance boost. It has been 
very rarely used in OS's so far, so there may be lots of disks
out there that do not implement it correctly but still pass for
SCSI/SCSI-2 disks when tested.

When Installing Solaris 2.1 off the CD on the Toshiba MK-538FB,
everything seems fine, and the install ends with no errors. 
Then, when the disk first boots, it starts yelling about 
tag-queuing errors and panics. THIS BOOT CORRUPTS THE
DISK LABEL. The next boot will panic saying that the disk
label is corrupt, and that the disk claims to have less
blocks than the label says it has. Fixing the disk label
requires a relabeling of the disk using format, after defining 
the disk type from scratch. The disk must be undergo a hard-reset 
(power off/on) before this is done.

The workaround is (obviously) to turn off SCSI tag queuing in 
the Solaris 2.1 kernel. Unlike 4.1.x, this can be done without
a kernel patch, by modifying /etc/system. The following line
must be added to the end of the file :

scsi_options=0x78

See /usr/include/sys/scsi/conf/autoconf.h for details on the
different scsi_options bits.

The change MUST BE DONE BEFORE the system boots the first time,
or the disk label will be corrupted by the first boot. Follow
this procedure when installing Solaris 2.1 off the CD :

1.)  Boot the Solaris 2.1 CD.

1.5) If your disk needs formatting, exit to the shell when you
     have a chance, and format the disk. Then return to the
     installation procedure by running suninstall.

2.)  Run through the installation setup procedure normally.

3.)  Start the installation. The system will ask you if you want
     to reboot after the installation is complete, *** SAY NO !!! ***.

4.)  When the installation is done, you will get the # prompt.
     You are still running Solaris off the CD (which has tag 
     queuing turned off when IT boots). Mount the newly
     installed disk's root partition using :

     mount /dev/dsk/c0t3d0s0 /mnt

5.)  edit (using vi) /mnt/etc/system, and add the following line at
     the end of the file :

     scsi_options=0x78

6.)  reboot.

**********************************************************************

I hope this summary is of help to people considering buying third
party drives for use with Solaris 2.1, or using Solaris 2.1 on
already installed third party drives. Perhaps this should go in 
some FAQ...

Many thanks to the following people for their helpful data and tips :

Steven Grimm	(koreth@spud.Hyperion.COM)
Jerry Gilliam	(Jerry.Gilliam@Eng.Sun.COM)
Sharon Azulay 	(sharon@eandm.com)
Lupe Christoph  (ukw!lupe@spud.Hyperion.COM)
Andy Chittenden	(asc@concurrent.co.uk)
Randy Green	(optimg!rgreen@uunet.UU.NET)
Roger Schwarze	(rsw@uwbln.uniware.de)
Leonard Mills	(len@contec.COM)
Randy Meyers	(rjmeye1@afterlife.ncsc.mil)
Len Evens	(len@math.nwu.edu)

-- Gil.
-- 
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-- Gil Tene			"Some days it just doesn't pay     -
-- devil@imp.HellNet.org	   to go to sleep in the morning." -
-- devil@diablery.10A.com 					   -
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Newsgroups: comp.sys.sun.admin,comp.unix.admin