SCSI geometry calculation?

[Nate Lawson]

I am reviewing our current geometry calculation and have a few questions.
Here is what I found in my review.

Most drivers use >1G: 255/63, else 64/32.  Exceptions are:
* aac - >=2G: 255/63, >=1G 128/32, else 64/32
* aha - same
* amr - >2G: 255/63, else 64/32
* asr - >4G: 255/63, >2G: 128/63, >1G: 65/63, else 64/32
* ata-raid - always 255/63
* bt - same as aha
* ciss - 255/32 if fault_tolerance is invalid else what the logical drive
reports.
* mlx - if MLX_GEOM_256_63 set: 255/63, else 128/32.  Since nothing seems
to set mlx_geom, 128/32 is probably always used.
* mly - same
* pst - always 255/63
* twe - >2G: 255/63, else 64/32

Some of these seem to be bugs, especially for volumes exactly on a
boundary (2G).  Since many of the stranger ones are RAID controllers, they
won't have to support drive portability to other controllers.  What should
actually be done in CALC_GEOMETRY?

-Nate