Re: New Feature Idea: Compress swap file
Ard van Breemen (ard@cstmel.hobby.nl)
Mon, 23 Feb 1998 16:00:30 +0100 (MET)
On Sun, 22 Feb 1998, Trevor Johnson wrote:
> > Since the real geometry isn't known to the driver, this would be a useless
> > thing to try.
> Isn't it known for ST-506 disks, floppies, and SCSI tapes (is it possible
> to swap to tape?)?
Well, it is only known for ST-506 disks, certain floppy controllers (the
pc floppy), but these are outstanding examples of bad design. Commodore
had perfect IEEE-488 floppy subsystems (actually they were file servers)
that had at least 4 zones of differing numbers of sectors/track. They
advised to use double density floppy's for the 1MB format, because the
single densitys had to much errors. The single density floppys contained
as much errors as the high density 51/4" floppys later used in PCees...
For (scsi) tapes the number of tracks is probably known, but I cannot
believe the complete tapesize is known until written.
And no, scsi tapes probably can not be used for swap. I know of older
HP IEEE488 tape streamers that not only could seek, but could seek AND
write. But the normal way of taping is to write and append, not rewrite.
If you want to rewrite information your tape must at least be formatted.
Some streamers can be used as an ro fs, but they have to at least support
block seek...
--
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