Magnetic tape filesystem

Dave G4UGM dave.g4ugm at
Mon Feb 9 16:34:46 CST 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Chuck
> Guzis
> Sent: 09 February 2015 19:42
> To: General at; Discussion at and Off-
> Topic Posts
> Subject: Re: Magnetic tape filesystem
> On 02/09/2015 11:00 AM, Peter Corlett wrote:
> > JOOI, why was there such a need to sort large datasets back in the
> > mainframe era?

Performance? Where I worked our master file was small by modern standards, a
mere 4million record, but it took up 14 reels of tape. The update program
had many tricks to speed things up...

> Knuth's book's title gives a hint.  He called it "Searching and Sorting".
The two
> go hand in hand.
> I think the simple answer is that it's easier to search sorted data,
> when said data is offline--i.e. hanging in a slot in a tape rack, or in a
drawer in
> a card cabinet.  Nowadays, when everything can be kept online, it's
> less important than it used to be.
> --Chuck

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