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Date:      Wed, 5 Jun 1996 22:54:18 -0700 (PDT)
From:      Michael Dillon <michael@memra.com>
To:        Dror Matalon <dror@hopf.dnai.com>
Cc:        freebsd-scsi@FreeBSD.ORG, freebsd-isp@FreeBSD.ORG
Subject:   Re: ERROR info:747d9d asc:11,0 Unrecovered read error, other SCSI issues
Message-ID:  <Pine.BSI.3.93.960605224614.11961D-100000@sidhe.memra.com>
In-Reply-To: <Pine.NEB.3.93.960605172234.999K-100000@mars.dnai.com>

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On Wed, 5 Jun 1996, Dror Matalon wrote:

> Quantum XP34300W 4.3 Fast Wide SCSI drives on a pentium 133
> as our news machine.

News servers eat drives. No matter what type of drive, they just wear out
and die.

> 2. My number 1 frustration with FreeBsd/Unix on a PC is related to
> the number of SCSI errors that we're running into. We might be at
> fault for not running the computer room  cool enough, 

Computer room??? How about the case where the drives are? Most clone cases
have NO (that's zero) airflow engineering done. The only way to be sure
that the drives are running cool enough (especially 7200 RPM drives) is to
mount them with space in between (an inch or so) and mount extra fans that
blow air across the top of the drive. When you open the case and remove
the bad drive, stick your finger on top. If it burns so badly that it
blisters, you need more cooling. Even if it's only hot, add more airflow
anyway.

> recently started using Granite's custom made SCSI cables. Still
> we've had close to 20% mortality rate on our SCSI disks. Are other
> people also experiencing these kind or problems?

Almost everybody who runs news servers. Go into your machine room any time
day or night and you hear drives rattling constantly. Go put your ear
against the news server, that's the one that NEVER stops rattling. The
others actually go in fits and starts. 

It helps to really cool things down a lot, i.e. air conditioned machine
room that you need to put on a sweater when you go in. It also helps to
use RAID (http://www.mylex.com DAC960SI) because it lessens the physical
activity on any one drive to some extent. And the special fans to blow air
across the top of each individual drive. The nice thing about a DAC960 is
that with a proper hot-swap chassis and RAID 5, replacing a drive doesn't
shut anything down.


Michael Dillon                                   ISP & Internet Consulting
Memra Software Inc.                                 Fax: +1-604-546-3049
http://www.memra.com                             E-mail: michael@memra.com




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