🚀 go-pugleaf

neil@nook.demon.co.uk (Neil Trotter) wrote:

>Are you sure about this, Peter?  This is interesting because I *believe* the
>last implementation of DRVSPACE I used (the one which came with DOS 6.2)
>used an ALU size of 8,192 bytes, I *believe* regardless of partition size.
>The Slack Space scourge was still an issue, though on a reduced scale for
>larger partitions.
>
>If what you're saying (about eliminating slack space at the end of clusters)
>is correct, then DRVSPACE must have been improved upon since my last
>misadventure with it ...
>
>Can anybody clear this up, just so we're not left wondering?

Here's my understanding of it (hopefully correct!):

Drivespace creates a single file on your drive, called drvspace.000
(and .001, .002, ... etc depending upon how many compressed volumes
you have). Since a compressed volume is one huge file, it will clearly
fill every cluster it can, perhaps with the exception of one. 

I tried your 'echo x>fred' method to determine cluster size on my
340Mb disk. I get 8192 bytes, and on an EZ135 removable disk
(formatted 127Mb) I get 2048 bytes - both exactly as you suggested. My
hard drive is compressed, so I did this on the uncompressed portion.
Out of interest, I tried it on the compressed portion and got a zero
cluster size! This is not really surprising at all, of course, because
the free space quoted for a compressed drive is just an estimate which
won't be altered by a piddly little file being added. The cluster size
is really the same as on the uncompressed portion, but it isn't an
issue as all of the space within all of the clusters in the compressed
volume is available for filling. Each new file you add, or change, is
just a part of a bigger file (drvspace.000).

Incidentally, I've been using disk compression for five years now. I
started with Stacker in 1991, and I've been through the various
incarnations of Doublespace/Drivespace up to the latest version,
Drivespace 3. Never had any trouble with any of 'em. Maybe I've been
lucky...






Jim Fitzpatrick
jim@jfitz.demon.co.uk