From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Wed, 31 Dec 1997 00:49:08 -0600
From: G. David Butler gdb@dbSystems.com
Subject: [9fans] Re: etherelnk3.c
Topicbox-Message-UUID: 6f5db098-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19971231064908.9bFZkHrStIFNGGOijmDM3-fgOoextP1lEw0lC9jRwbo@z>

>>When PCI finally settles down and gets as reliable as 154x's on
>>the ISA bus, I'll move.  Of course a good SCSI adapter design
>>would be nice.  I hate the 294x.  Does anybody have any experience
>>with the Qlogic board?  (http://www.qlc.com)  It looks like
>>a good alternative.
>
>i know of drivers available for 3 other controllers:
>	buslogic (mylex)
>	dpt
>	ncr (symbios) 53c8xx series

Thanks for the info.

But how do those controllers compare to the Qlogic board or
the Adaptec 294x?  The QLogic board has two processors like
the 154x and you only get one interrupt per SCSI command.
(like the 174x. you can get many completed per interrupt on the
154x.) The 2940 gives interrupts as targets disconnect/reconnect!
The host processor has to almost manage the SCSI bus directly.
A 154x will even retry a command to a BUSY LUN for you without
issuing another interrupt.

On my systems I like to have as many SCSI busses as I can
so I can have a reasonable number of targets per bus.  So
having many cards that need to be patted on the butt every
time a target blinks is not good for getting any other
work done, like servicing ethernet clients.  I can put 4
154x's in a system with a P5/133 and have plenty of CPU
to keep the ethernet lit.  How many 2940's can you run with
a P5/133 with targets disconnecting/reconnecting like
crazy because of all the random I/O?