Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!killer!pollux!dalsqnt!rpp386!pigs!haugj
From: haugj@pigs.UUCP (Joe Bob Willie)
Newsgroups: comp.sys.ibm.pc
Subject: Re: ST251 28ms drive
Summary: don't forget the settling time.
Message-ID: <383@pigs.UUCP>
Date: 31 Aug 88 16:21:22 GMT
References: <1741@spdcc.COM>
Reply-To: haugj@pigs.UUCP (Joe Bob Willie)
Organization: Big "D" Oil and Gas
Lines: 22

In article <1741@spdcc.COM> eli@spdcc.UUCP (Steve Elias) writes:
>the st251 seems much slower than other 28ms drives that i've used.
>any clues, folks?  perhaps it has a slower data transfer time, too.

track-to-track time includes settling time, which may be higher on
the 28ms drive.  average access time is 1/3 stroke time and only
includes one settling time.  so it is possible for the settling time
to be higher on a `faster' drive and still have a lower 1/3 stroke
time.  i suspect such a drive is slower in reality because many
small seeks would cause the settling time to become a larger and
larger factor.

the data transfer TIME is determined by the interleave factor and
controller, etc.  the data transfer RATE, which depends on the
drive logic (pete holz{man,berg} (sp) is i believe the resident disk
hardware guru around here)  is fixed by the rotational speed of
the disk and the amount of data on each track.
-- 
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