Path: utzoo!mnetor!uunet!husc6!think!ames!ubvax!weitek!sci!raymund
From: raymund@sci.UUCP (Raymund Galvin)
Newsgroups: comp.sys.amiga
Subject: Re: Warm Reboot and Hard Disk Noise
Message-ID: <20927@sci.UUCP>
Date: 6 May 88 05:35:33 GMT
References: <8804300422.AA18746@decwrl.dec.com> <12083@tut.cis.ohio-state.edu> <2897@tekigm2.TEK.COM>
Organization: Silicon Compilers Systems Corp. San Jose, Ca
Lines: 35
Summary: could there be a better way?

In article <2897@tekigm2.TEK.COM>, phils@tekigm2.TEK.COM (Philip E Staub) writes:
> Don't be so hasty to reject the explanation. What you are referring to by
> the 20-60 millisecond range is the *seek* time. What Ethan was referring to
> is a completely separate function known as "recalibration", which does not
> use a standard seek. This function literally starts and stops the motion of
> the head for each track it crosses, resulting in *much* longer times to 
> get across the multiple hundreds of tracks on a hard disk. Imagine the time
> it would take to do a seek from track 0 to track 599 if you had a 600
> track floppy, and you're more in the range of the time it takes to do a 
> recalibrate.
> 
> 
> Phil
> 

I didn't mean to reject the explanation.  It was, as many people  pointed out,
probably correct.   My real intention was to criticize the behavior
of the disk controller/software during reboots.   Ok, maybe I was a bit 
hasty.  Let me put it another way:

I have a miniscribe hard disk with an ST506 interface that usually 
makes 2 to 3 seconds of noise during the recalibration process when used
with my amiga.   The same drive never made any objectionable noise during 
the recalibration process when used in my PC clone.   

According to the my drive's manual, the drive will ignore requests to step the 
heads out past track 0 or in past the head parking cylinder.  This means it is 
not necessary to check for track 0 after every step during a reclibration 
process.   Just do one huge seek and verify that you're at track zero when the
seek completes.   If some disk drives aren't intelligent enough to handle 
this, then the amiga's recalibration routine seems to be a reasonable (but 
noisy) compromise;  otherwise, the amiga's drive recalibration routine could 
be made quieter.

Ray Galvin