>I have an Quantum 270 MB hard disk.  It was reinitialized with Apple HD SC
>Setup vers. 7.3.5, and given a approx. 215 MB root&usr partition, and an
>approx. 36 MB swap partition.

Steven,

Strange problem.  Mkfs finds the partitions by reading the Disk Partition 
Map. There's one entry for each partition on the disk including the Map 
and Driver partitions. At first guess I'd say the problem is with the way 
Apple HD SC Setup initialized the disk.  I recently re-partitioned an 
Apple disk with this utility on my PPC Mac, but when I took it to my 68K 
Mac it wouldn't mount. I decided to re-partition it with a variant of the 
APS formatter. When I identified the disk I wanted to partition the APS 
formatter told me the Partition Map was damaged and that it showed one 
less block allocated than the number in use!  I suspect that's what 
happened to you as well and leaving a dangling unused partition solved 
the problem, since Mkfs reads only the number of Partition Map entries 
identified by the Partition Map size in it's entry. It would be 
interesting to see what results you obtain with older versions of HD SC 
Setup or with FWB.

Hope this helps,
-bob