Path: utzoo!attcan!uunet!husc6!think!ames!oliveb!amdahl!mat
From: mat@amdahl.uts.amdahl.com (Mike Taylor)
Newsgroups: comp.arch
Subject: Re: Why no disks with two HDAs ?
Keywords: diskdrives, headdiskassemblies
Message-ID: <8dly9ed7S71010boqkE@amdahl.uts.amdahl.com>
Date: 20 Jun 88 16:32:36 GMT
References: <2351@uklirb.UUCP> <2440@winchester.mips.COM>
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 20

In article <2440@winchester.mips.COM>, cprice@mips.COM (Charlie Price) writes:
> 
> Two follow-on big disks were the 3370 and 3380.
> In addition to having two HDAs, they took the step of having
> two separate actuators (head arms) inside each HDA.
> For some reason, IBM still wanted to build physically large HDAs
> with a large number of platters and a lot of data so they made
> the math come out right by having two actuators.
> The current technology really favors building the same sort
> of system out of a larger number of smaller HDAs.  It isn't
> clear to me that IBM's choice made technological sense.

They probably had a manufacturing technology for the 14" platters
that they didn't want to replace.  I expect their sums said that
using old platters and developing new head technology - the thin-film
head - was the best economic choice.
-- 
Mike Taylor                        ...!{ihnp4,hplabs,amdcad,sun}!amdahl!mat

[ This may not reflect my opinion, let alone anyone else's.  ]