Path: utzoo!attcan!uunet!husc6!mailrus!tut.cis.ohio-state.edu!bloom-beacon!gatech!rebel!didsgn!root
From: root@didsgn.UUCP (didsgn)
Newsgroups: comp.arch
Subject: Re: Why no disks with two HDAs ?
Summary: There are other disks with 2 HDA
Keywords: diskdrives, headdiskassemblies
Message-ID: <285@didsgn.UUCP>
Date: 18 Jun 88 12:43:14 GMT
References: <2351@uklirb.UUCP>
Organization: Digital Design Inc., Norcross GA
Lines: 31

In article <2351@uklirb.UUCP>, kirchner@uklirb.UUCP (Reinhard Kirchner) writes:
> 
> Hello,
> recently I once again learned about IBM disk drives which have two
> head-mechanisms ( Head-Disk-Assemblies , HDA ) per spindle.
> They have several drives of this kind, including the big 3380.
> 
> Now:
> - why doesn't anybody else produce drives with two HDAs ?
>   ( or does somebody whom I do not know ?, and then why ? )
> . Is it not worth the effort, patented by IBM, or what is the reason ?
> 
> R. Kirchner


A few other manufacturer are selling drives with two HDAs. Here is a few:

	AMPEX is (or was a few years ago) building a FIX/REMOVABLE disk
	drive with 2 HDA. One HDA is taking care of the cartrige part of the
	drive (16 Mb unf.) and another is taking care of the fix part of it
	(16 to 64 Mb unf). It is possible to activates both HDA as a single
	one or (and this depend on the interface&software driver) as 2 inde-
	-pendant ones.

	IBIS is building a parallel transfer drive know as the 1400. It trans-
	fer data at 12Mb burst/10 Mb sustain per second. It's capacity is 1.4 Gb	and it contains 2 HDA with 16 heads each. Both HDA are in sync. They are	using 2 HDAs to solve an inertia problem of 1 HDA carrying 32 heads.

Jean-Luc Chatelain
...!gatech!rebel!didsgn!jlc

Standard disclaimer applies....