Date: Fri, 29 May 1998 12:23:55 -0600 From: "Justin T. Gibbs" <gibbs@plutotech.com> To: Chris Timmons <skynyrd@opus.cts.cwu.edu> Cc: "Justin T. Gibbs" <gibbs@plutotech.com>, scsi@FreeBSD.ORG Subject: Re: Quantum Atlas II warning Message-ID: <199805291828.MAA24115@pluto.plutotech.com> In-Reply-To: Your message of "Fri, 29 May 1998 11:19:33 PDT." <Pine.BSF.3.96.980529111212.22933I-100000@opus.cts.cwu.edu>
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> >Although I haven't yet seen the ugly failure syndrome (yet) that you >alluded to, do you suppose that the later firmware will help with this sad >situation? This is the repo disk for cvsup.freebsd.org: > >da2: <QUANTUM XP34550W LXY4> Fixed Direct Access SCSI2 device >da2: Serial Number PCB=2011300001 ; HDA=184704251342 >da2: 40.0MB/s transfers (20.0MHz, offset 8, 16bit), Tagged Queueing >Enabled >da2: 4341MB (8890760 512 byte sectors: 64H 32S/T 4341C) >(da2:ahc1:0:4:0): tagged openings now 31 >(da2:ahc1:0:4:0): tagged openings now 30 >(da2:ahc1:0:4:0): tagged openings now 29 >(da2:ahc1:0:4:0): tagged openings now 28 >(da2:ahc1:0:4:0): tagged openings now 27 >(da2:ahc1:0:4:0): tagged openings now 26 >(da2:ahc1:0:4:0): tagged openings now 25 >(da2:ahc1:0:4:0): tagged openings now 24 I'm afraid that a firmware upgrade will not address this problem. You can artificially force the tag counts higher for the drive, but the, somewhat arbitrary count of 24, was chosen so that QUEUE FULLs don't occur "all the time" during write operations. The cache on the Atlas II fills really easily, so the tag count tends to drop, but we don't allow it to fall below 24 so that read operations still benefit from tagged queuing. >Our news server, now running 2.2.6-STABLE+CAM is noticeably revitalized - >throughput increase with CAM was substantial as others running >-current+CAM had reported. That system has all barracudas and hasn't had >to dynamically lower the tagged openings at all. If you really pound the disks, it should drop to 63, but no lower. The Barracudas have a built in limit of 63 transactions. >CAM really, really helps (but you knew that :) 8-) >-Chris -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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