From mboxrd@z Thu Jan 1 00:00:00 1970 From: Denny Page Subject: Adaptec aix79xx performance Date: Fri, 02 Dec 2005 23:35:44 -0800 Message-ID: <43914AD0.2050007@cococafe.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.cococafe.com ([64.142.30.235]:8842 "EHLO mail.cococafe.com") by vger.kernel.org with ESMTP id S1751186AbVLCHfp (ORCPT ); Sat, 3 Dec 2005 02:35:45 -0500 Received: from marvin.cococafe.com (gw.cococafe.com [64.142.30.237]) by mail.cococafe.com (Postfix) with ESMTP id 740B8590 for ; Fri, 2 Dec 2005 23:35:45 -0800 (PST) Received: from [192.168.0.2] (marvin.cococafe.com [192.168.0.2]) by marvin.cococafe.com (Postfix) with ESMTP id D8AFDB03 for ; Fri, 2 Dec 2005 23:35:44 -0800 (PST) Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Linux SCSI Mailing List Hello, I have a question regarding the support condition of the aic79xx driver. I am running kernel version 2.6.14 (gentoo) on a dual processor system PCI-X system. I am using an Adaptec scsi adapter to run an HP Ultrium tape drive. Nothing else is attached to the controller. I was previously using an Adaptec 29160N (aic7892), which is a 32 bit, 66Mhz controller. With this controller, the tape was not able to maintain full streaming, or achieve full speed. Average rate was approximately 27MB per second. In order to address the performance problem, HP recommended that I change to a 64 bit U160 or U320 controller. I've put in an Adaptec 29320ALP-R (aic7901), which is a 32 bit, 133Mhz controller. With this controller, performance has dropped to an abysmal 2.7MB per second! I am running the controller at 133Mhz, but I have also tried locking it to 66Mhz with no effect. I am using the same cable with both controllers, and the terminator is built into the cable. Nothing stands out in /var/log/messages. So, can anyone offer ideas as to why the 79xx controller performs at one tenth the rate of the 78xx controller and how to fix it? Any help appreciated. Thanks, Denny