Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!synsys!jeffj
From: jeffj@synsys.UUCP (Jeff Jonas)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Low-level format of hard disk
Summary: I see no way it can be harmful
Message-ID: <431@synsys.UUCP>
Date: 12 Oct 90 02:13:35 GMT
Reply-To: jeffj@synsys.UUCP (Jeff Jonas)
Organization: Jeff's House of Electronic Parts
Lines: 49

[]
In reply to the current thread asking:
> Please explain how doing a low level format causes 'wear' on the heads.

I've seen enough of this garbage.
I've handled many hard drives (5.25" and 8" winchester, 14" platters),
and formatting is nothing more than writing a
predetermined pattern on every track.
The head starts at one end and steps across one track at a time,
which is gentler than usual use to all the mechanisms and even
the power supply (linear motors draw a lot of power when slewing the
heads across the disk).

[In the factory, formatting is done differently using
specialized machines to stress the medium and give the most
pessimistic defect list.
Here we are discussing normal customer formatting]

Look at the interface wires: there are NO special signals for formatting.
Just the usual write and seek signals.
The write signal is TTL, so the controller cannot give
a stronger or weaker signal.
There is no external control of the read/write amplifiers.

As to the heads actually touching the platters: I've heard that
in the eternal quest for higher density, there are SOME disks
where the heads float on a layer of lubricant rather than flying
on air.  This allows the heads to get closer to the disk thus
allowing more dense writing/reading.
If you leave the heads in the same place for too long, you risk
wearing away the lubricant, so these disks have built in controllers
that automatically move the heads when the disk is idle.
Then again, this was from a technician that couldn't understand how
to select the optimal sector size.


> If the machine is an AT, the disk will have been formatted by the
> manufacturer before shipping. It is not recommended that you re-format

Perhaps the drive is formatted (it had to be formatted to some extent at
the factory for generating the defect map),
but your controller may not understand the format.
Not only is the disk format controller specific,
you may choose different skewing, interleaving, sector size, etc.
This is why disks usually come with a floppy with a formatter
(Seagate drives come with the Ontrack Disk Manager).

Jeffrey Jonas
jeffj@synsys.uucp