Path: utzoo!mnetor!uunet!husc6!bloom-beacon!atheybey@PTT.LCS.MIT.EDU
From: atheybey@PTT.LCS.MIT.EDU
Newsgroups: comp.sys.amiga
Subject: Re:  Warm Reboot and Hard Disk Noise
Message-ID: <8805031431.AA03262@PTT.LCS.MIT.EDU>
Date: 3 May 88 14:31:29 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: atheybey@PTT.LCS.MIT.EDU
Lines: 37
To: nntp-poster@PTT.LCS.MIT.EDU

Repository: PTT

Originating-Client: flower


Raymund Galvin writes:
:In article <12083@tut.cis.ohio-state.edu>, erd@tut.cis.ohio-state.edu (Ethan R. Dicks) writes:
:< 
:< Your drive buzzes on warm start, (like mine too), because the controller 
:< forgets where the heads are when reset, and must get the heads back to a
:< known place.  Since on the Amiga, the most likely place for the heads to be is
:< over the root track,and most Amiga owners only have one BIG partition, that's 
:< a lotta tracks to cover when pulling the heads to the edge of the disk. The
:< noise you hear is as a result of either the hddisk.device stepping the tracks
:< very fast to 0, or a command sent to the drive itself, telling it to reset the
:< heads (I don't know which, because I don't know much about the hddisk.device)
:< 
:
:I doubt it. Two seconds of noise for a simple seek.  Give me a break.  
:These days many drives are rated as having average seek times in the 
:20-60 millisecond range.  An average seek for a drive translates to one 
:third of a full stroke seek.   The absolute worst case seek shouldn't be more 
:than 3 times the average seek time (usually it will be less).  I would 
:bet that whoever wrote the code that is messing around with the hard 
:disk (during reboots) is doing something silly.   I wish someone
:from Commodore would explain what is happening.
:

I believe that Ethan is correct except for the word "fast".  When the
hard drive is reset (or powered up), it does not know the track that
the heads are on.  It therefore steps the heads toward track 0
*slowly*--10s of milliseconds *per track*--until it notices that the
heads have hit the physical stop at track zero.  If it did this at
full speed, it would quickly destroy the heads by bashing them against
the stop.  I think that this is a function of the drive, not the controller.

I have heard the same noise on hard drives on IBM PCs as well.  It is
entirely normal, and is certainly not the result of any particular
hard disk code on the Amiga.

Andrew Heybey
atheybey@ptt.lcs.mit.edu