From: panlilio@acs.ucalgary.ca (Victor P. Panlilio)
Subject: Re: Whats this "Thermal Recalibration" on Quantum Drives ?
Summary: Thermal recalibration on hard drives
Article-I.D.: acs.93Apr06.172811.42754
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Organization: The University of Calgary, Alberta
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Nntp-Posting-Host: acs3.acs.ucalgary.ca


In article <1993Mar26.195307.25146@midway.uchicago.edu> gary@midway.uchicago.edu writes:

>Whether the drive is hooked up to the computer or not, the LPS240
>makes a "disk seek noise" every 20 seconds.  This is consistent 
>and will continue as lomg as the drive is powered up.  Even if 
>I disconnect the drive from the computer, this "drive activity"
>continues at 20 second intervals.
>
>Someone tried to tell me the drive was doing a "Thermal Recalibration".
>
>Not knowing beans about the internal physical workings of the lastest
>disk drive technology.... I guess I might believe anything.
>
>Whats the scoop on this standalone "drive activity" every 20 sec?

I can only comment on thermal recalibration in general. Some new
drives perform it in order to increase overall integrity of data
writes. Basically, the firmware instructs the actuator to perform
a test to see if the data tracks are within a certain physical
tolerance, since when the media heats up or cools down, *some*
track drift is inevitable, and the drive has to monitor it. This
becomes especially critical at very high recording densities, and
so was used primarily on very large-capacity mechanisms, but it
seems to be finding its way into more smaller drives as a way of
boosting the drive's long-term reliability and MTBF ratings.

I first became aware of thermal recalibration when it was pointed
out that the technique conflicts with prolonged write times when
digitizing, say, audio or video to hard disk. Some manufacturers
explicitly state that drives with thermal recalibration are NOT
to be used for applications that have prolonged disk writes.

Hope this helps.

Victor
