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From: mc68020@gilsys.UUCP (Thomas J Keller)
Newsgroups: comp.misc
Subject: disk drive life expectancies
Message-ID: <1118@gilsys.UUCP>
Date: Sun, 30-Aug-87 15:23:51 EDT
Article-I.D.: gilsys.1118
Posted: Sun Aug 30 15:23:51 1987
Date-Received: Fri, 4-Sep-87 05:46:19 EDT
Organization: Consequently Computers, Santa Rosa, Ca
Lines: 31
Keywords: MTBF, power cycling, lifespan


   In general, it is my considered opinion that leaving a hard-disk based
system powered up is a good thing, as it seems to reduce hardware failures.
An interesting situation arises, however, when one is using consumer grade
winchester drives with low MTBF (mean time between failure) ratings.

   Take the Seagate ST-225 piece of trash, for example.  A very popular
drive, largely due to its low price, this drive has a 4000 hour MTBF.  Now,
a little simple arithmetic will reveal that 4000 hours is sightly less than
six months.  Of course, there is no guarantee that the drive *WILL* fail in
4000 hours, only that the statistical mean over the sample population used
in this test was 4000 hours.

   Nevertheless, the question arises:  which is the better approach with such
a low-quality drive?  To leave it powered up, thereby frittering away a LARGE
percentage of its expected lifespan, or to power-cycle the system, thereby
stressing the drive (and the rest of the system) with THOSE problems?

   I honestly cannot decide which makes more sense.  What makes *REAL* sense
is to avoid consumer-grade disk drives like the plague, and stick to the
commercial-grade, higher quality devices.  Sometimes immediate economics
make such a move impossible, however.  What to do, what to do?

   Comments or suggestions via email, please.  Flames and smart-a** remarks
> /dev/null.


-- 
Tom Keller 
VOICE  : + 1 707 575 9493
UUCP   : {ihnp4,ames,sun,amdahl,lll-crg,pyramid}!ptsfa!gilsys!mc68020