Re: 9-track tape drive (Was: Re: versioned filesystems in linux)

From: "H. Peter Anvin" <hpa@zytor.com>
To: John Bradford <john@grabjohn.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 9-track tape drive (Was: Re: versioned filesystems in linux)
Date: Fri, 25 Apr 2003 14:22:55 -0700	[thread overview]
Message-ID: <3EA9A72F.4030505@zytor.com> (raw)
In-Reply-To: <200304252121.h3PLLwSX002318@81-2-122-30.bradfords.org.uk>

John Bradford wrote:
>>>Of bigger concern is that the inter-block gap is only 0.5 (or maybe 0.75
>>>inches, the memories are dim ;) - and you need to be able to stop and then get
>>>back up to speed in that distance (or decelerate, rewind, and get a running
>>>start).
>>>
>>
>>No, you don't.  You just need to make sure you don't have the head
>>active while you overshoot.  Performance will *definitely* suffer if
>>you don't, though, since you'd have to rewind.
> 
> 
> Well, we could make our device dual speed, and either run at E.G. 60
> I.P.S. or 120 I.P.S. depending on whether we want to read a large
> block of data, or just one block that happens to be closer to the
> current head position than the distance we need to accellerate to 120
> I.P.S.
> 

Actually, as long as you get enough read speed across the head and can
actually measure the real speed you can presumably vary the speed
arbitrarily, all the way up to the breaking point of the medium.

	-hpa