[1280] in linux-scsi channel archive
Re: AHA 1542 driver performance questions
daemon@ATHENA.MIT.EDU (Jim Van Zandt)
Sat Jan 18 22:18:41 1997
To: David A Willmore <willmore@cig.mot.com>
Cc: linux-scsi@vger.rutgers.edu
In-reply-to: Your message of "Fri, 17 Jan 1997 13:36:32 CST."
<199701171936.OAA06172@po_box.cig.mot.com>
Date: Sat, 18 Jan 1997 21:27:00 -0500
From: Jim Van Zandt <jrv@vanzandt.mv.com>
In message <199701171936.OAA06172@po_box.cig.mot.com>, David A Willmore writes:
>I have recently aquired an aha1542A SCSI card. It works with the aha1542
>driver just fine, except that the performance isn't what I was expecting.
>...I get about 1.8 M/sec total from the five drives.
>
>My questions: (1) is this what I should expect? (2) does this driver do sync
>transfer on the SCSI bus and, if so, can I get it to tell me what speed it's
>doing it at? (3) does it do disconnect/reconnect?
From my Adaptec 1542A manual:
"High performance Bus Master DMA with selectable or programmable data
rates of up to 10 MBytes/second.
"Maximum synchronous SCSI transfer rate of up to 5.0 MBytes/second
"The AHA-1540A/1542A supports multithreaded SCSI initiator operation
through a simple mailbox protocol. The firmware accepts as many
Command Control Blocks (CCB's) as required and executes them from its
local RAM. The firmware controls all of the SCSI activity that a task
may require This includes: Arbitration, Selection, Disconnection,
Reconnection, and Command completion.
"Jumper block J1 is the large vertically oriented block of jumpers
located near the center of the host adaptor. Pin pair 1 is the
topmost pair of pins.
"Pin-pair 1 of jumper block J1 is the synchronous negotiation enable
jumper. The AHA-1540A/1542A will initiate SCSI synchronous
negotiation during initialization, or after a SCSI reset if this
jumper is installed. If the jumper is not installed, the
AHA-1540A/1542A will still support synchronous SCSI transfers, but a
different SCSI device must initiate the negotiation. Default is
jumper removed, synchronous negotiation disabled. If any attached
SCSI devices support synchronous transfer, the initiation of
negotiation should be enabled by both the AHA-154xA and the attached
devices to fully implement the SCSI synchronous negotiation protocol."
The fellow I bought my AHA1542A from had installed a replacement ROM
which made it equivalent to an AHA1542B (SCSI-2, if I remember
correctly). You might want to look into that.
- Jim Van Zandt
