From owner-freebsd-scsi@FreeBSD.ORG Tue Jun 27 13:25:36 2006 Return-Path: X-Original-To: freebsd-scsi@freebsd.org Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DEA9516A403 for ; Tue, 27 Jun 2006 13:25:36 +0000 (UTC) (envelope-from anderson@centtech.com) Received: from mh1.centtech.com (moat3.centtech.com [207.200.51.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6E1E643D67 for ; Tue, 27 Jun 2006 13:25:36 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from [10.177.171.220] (neutrino.centtech.com [10.177.171.220]) by mh1.centtech.com (8.13.1/8.13.1) with ESMTP id k5RDPZAH061186; Tue, 27 Jun 2006 08:25:35 -0500 (CDT) (envelope-from anderson@centtech.com) Message-ID: <44A131DE.3010702@centtech.com> Date: Tue, 27 Jun 2006 08:25:50 -0500 From: Eric Anderson User-Agent: Thunderbird 1.5.0.4 (X11/20060612) MIME-Version: 1.0 To: Jerlique Bahn References: <005901c699ec$7d70bdb0$6400000a@WKSTN501> In-Reply-To: <005901c699ec$7d70bdb0$6400000a@WKSTN501> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV 0.87.1/1564/Mon Jun 26 09:55:16 2006 on mh1.centtech.com X-Virus-Status: Clean Cc: freebsd-scsi@freebsd.org Subject: Re: Viewing SCSI errors.. X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 Jun 2006 13:25:37 -0000 Jerlique Bahn wrote: >>> I've added a tape drive to my server and the drive only seems to work at >>> 2MBps. The drive should be doing about 24MBps. The tape is a DELL 110T >> LTO2 >>> which runs at about 86Gb/hr. >>> >>> I am trying to diagnose where my problems could lie, and was wondering >> how I >>> could see if there are any errors in the communication between the tape >> and >>> the scsi card (320Mbps). I'm quite confident the speed issue is related >> to >>> the tape drive or the scsi chain. >>> >>> Your suggestions welcomed. >> >> How did you measure the 2MBps number? > > With iostat, eg > > # iostat 5 > tty amrd0 amrd1 sa0 cpu > tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id > 0 12 57.81 2 0.13 53.21 6 0.32 31.99 24 0.76 0 0 1 0 99 > 0 46 8.00 0 0.00 0.00 0 0.00 32.00 88 2.74 0 0 0 0 100 > 0 16 0.00 0 0.00 16.00 0 0.01 32.00 87 2.73 0 0 1 0 99 > 0 15 0.00 0 0.00 0.00 0 0.00 32.00 88 2.74 0 0 0 0 100 > 0 16 0.00 0 0.00 0.00 0 0.00 32.00 88 2.74 0 0 0 0 99 > > JB What tool was writing to the tape? Most of the time, tapes require you to stream the data evenly to it, to avoid 'shoe shining'. I usually use something like: tar -b 256 ... or use a buffering tool to buffer the data going to the tape device (use a pipe). You might try some various bs= arguments to dd, to see if you can get the throughput up. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------