From owner-freebsd-scsi@FreeBSD.ORG Fri Mar 11 23:58:59 2005 Return-Path: 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 DE38216A4CE for ; Fri, 11 Mar 2005 23:58:59 +0000 (GMT) Received: from bast.unixathome.org (bast.unixathome.org [66.11.174.150]) by mx1.FreeBSD.org (Postfix) with ESMTP id 23C1543D41 for ; Fri, 11 Mar 2005 23:58:59 +0000 (GMT) (envelope-from dan@langille.org) Received: from wocker (wocker.unixathome.org [192.168.0.99]) by bast.unixathome.org (Postfix) with ESMTP id 66FA83D4B; Fri, 11 Mar 2005 18:58:47 -0500 (EST) From: "Dan Langille" To: "Kenneth D. Merry" Date: Fri, 11 Mar 2005 18:58:47 -0500 MIME-Version: 1.0 Message-ID: <4231EA67.15143.56AB2BB5@localhost> Priority: normal In-reply-to: <20050311231347.GA43379@nargothrond.kdm.org> References: <4231D28B.28878.564DFBA1@localhost> X-mailer: Pegasus Mail for Windows (4.21c) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body cc: freebsd-scsi@freebsd.org Subject: Re: how does the scsi chain work? X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Mar 2005 23:59:00 -0000 On 11 Mar 2005 at 16:13, Kenneth D. Merry wrote: > On Fri, Mar 11, 2005 at 17:16:59 -0500, Dan Langille wrote: > > Hi folks, > > > > I added the following devices to my computer, all in one SCSI chain: > > > > sa0: Removable Sequential Access SCSI-2 device > > sa0: 20.000MB/s transfers (10.000MHz, offset 15, 16bit) > > sa1 at sym0 bus 0 target 6 lun 0 > > sa1: Removable Sequential Access SCSI-2 device > > sa1: 20.000MB/s transfers (10.000MHz, offset 15, 16bit) > > sa2 at sym0 bus 0 target 8 lun 0 > > sa2: Removable Sequential Access SCSI-2 device > > sa2: 20.000MB/s transfers (10.000MHz, offset 15, 16bit) > > > > Then I decided to do some concurrent testing. See below for details. > > The goal was really to test filling the tape. This exercises both > > the drive and the tape (all of which are used). > > > > Sometimes a single tar takes nearly 4 hours, sometimes it takes only > > 75 minutes. > > > > My question: It doesn't look like the load is shared evenly. Can > > someone talk a bit about this? That's a pretty general and wide > > question, I know... > > You might want to look at your media quality. You said that your drives > and media are used... > > In this case you even got a write error. That's pretty indicative of bad > media. (Or a drive that needs to be serviced I suppose.) But that's the tape filling up... surely? That's what the test does... fills the tape. Entirely. Usually, I see bad media with: Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): SPACE. CDB: 11 1 ff ff ff 0 Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): CAM Status: SCSI Status Error Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): SCSI Status: Check Condition Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): MEDIUM ERROR info:ffffffff csi:0,0,f,ba asc:11,0 Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): Unrecovered read error Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): Retries Exhausted Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): unable to backspace over one of double filemarks at end of tape Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): it is possible that this device needs a SA_QUIRK_1FM quirk set for it Feb 15 07:06:53 lux kernel: (sa0:isp0:0:4:0): tape is now frozen- use an OFFLINE, REWIND or MTEOM command to clear this state. > > [root@lux:/home/dan] # date && time tar cf /dev/nsa0 /usr && time > > tar cf /dev/nsa0 /usr && time tar cf /dev/nsa0 /usr && time tar c > > f /dev/nsa0 /usr && time tar cf /dev/nsa0 /usr && time tar cf > > /dev/nsa0 /usr ; date > > Thu Mar 10 22:31:57 EST 2005 > > tar: Removing leading '/' from member names > > > > real 75m15.394s > > user 0m45.666s > > sys 2m31.039s > > tar: Removing leading '/' from member names > > > > real 114m5.702s > > user 0m52.549s > > sys 2m45.939s > > tar: Removing leading '/' from member names > > > > real 156m18.091s > > user 0m51.538s > > sys 2m46.858s > > tar: Removing leading '/' from member names > > > > real 119m48.240s > > user 0m49.670s > > sys 2m45.721s > > tar: Removing leading '/' from member names > > tar: usr/home/bacula-restores/usr/X11R6/share/locale/bs/LC_MESSAGES: > > Write error > > > > real 195m0.408s > > user 0m38.779s > > sys 2m13.158s > > Fri Mar 11 09:32:26 EST 2005 > > > And you got another write error on this tape: > > > root@lux:/home/dan] # date && time tar cf /dev/nsa1 /usr && time tar > > cf /dev/nsa1 /usr && time tar cf /dev/nsa1 /usr && time tar cf > > /dev/n > > sa1 /usr && time tar cf /dev/nsa1 /usr && time tar cf /dev/nsa1 > > /usr ; date > > Thu Mar 10 22:53:40 EST 2005 > > tar: Removing leading '/' from member names > > > > real 103m35.344s > > user 0m50.394s > > sys 2m44.732s > > tar: Removing leading '/' from member names > > > > real 112m40.647s > > user 0m50.555s > > sys 2m46.049s > > tar: Removing leading '/' from member names > > > > real 152m45.638s > > user 0m52.656s > > sys 2m46.040s > > tar: Removing leading '/' from member names > > > > real 201m0.014s > > user 0m53.838s > > sys 2m51.051s > > tar: Removing leading '/' from member names > > tar: usr/home/bacula- > > restores/usr/src/contrib/ncurses/form/fld_link.c: Write error > > > > real 93m59.622s > > user 0m22.483s > > sys 1m8.356s > > Fri Mar 11 09:57:41 EST 2005 > > With a tape, if it can't write in one area, it'll skip down the tape to try > to find an area it can write to. So you may just be running into bad areas > on the tape. > > I would recommend buying some new media that is speced to work on those > drives, and then try it out. If you still have variable performance and > write errors, then you may have a drive problem. sa2 was writing to new media. > Don't forget to run a cleaning tape through if those drives use cleaning > tapes. Yep. I got to get me some of that. -- Dan Langille : http://www.langille.org/ BSDCan - The Technical BSD Conference - http://www.bsdcan.org/