CDC WREN IV is Lying!!!

[Andrew Herbert]

In <2001 at lzga.ATT.COM> apb at lzga.ATT.COM (Amrit Bains) writes:
>I just brought a CDC WREN IV Model Number 94171-307  ( 8-).

Me too ;-).

>The disk drive has 320 MB of disk space.
>But when I added it to my system it showed only 286 MB  ( 8-( ).
>Does anyony know why this is happening!!!

Well... According to the OEM manual, the -307 means it comes formatted for
307MB.  A table in the abovementioned indicates that if formatted with 512 byte
sectors and no spare sectors on each track the drive will end up with 307MB.
To get 320MB, format with 1024 byte sectors and no spares.  From memory, having
one spare 512 byte sector per track (or perhaps they meant cylinder?) results in
a 301MB drive.

Andrew

p.s. Anyone know how to select what read-ahead the drive uses with its cache?
Also, what is the performance difference between the -307 Wren IV and the
-344?  (i.e. how much difference does synchronous scsi make?)  Thanks.