Wren V/VI 700MB Hard Disks?

[Brent Chapman]

# Has anyone tried dropping in the new Wren V 702MB hard drives or Wren VI
# 766MB hard drives with embedded ESDI/SCSI controllers into your Sun 3 yet?
# If so, what SCSI controller board and OS were you using and did you
# experience any unusual installation problems?

I've got a pair of the Wren V 702 MB disks, one on each of two 3/60s
running 3.5.  They work great! 

Formatting and partitioning them can be slightly tricky because the disk
has a variable number of sectors per track (more sectors on outer tracks),
and the UNIX filesystem assumes a fixed number of sectors per track.  You
just lie to UNIX about how many sectors per track there are, giving it
some "average" number that gets you all the sectors, though they won't be
on the tracks UNIX thinks they are.  This doesn't really matter, though,
because it turns out that, with SCSI disks, the track/sector information
is _only_ used within the kernel to try to optimize head seeks; all
communications to the SCSI controller are of the form "give me sector #
so_and_so", where so_and_so is an absolute sector number (it's up to the
controller to figure out what head/track/relative_sector this translates
to).  Thus, you can get to all the sectors, but the optimization attempts
in the kernel definitely _aren't_ optimizing; I doubt if they're hurting
things too much, though.

I used "1547 cylinders 15 heads 50 sectors/track" to format mine.


-Brent
--
Brent Chapman					Capital Market Technology, Inc.
Computer Operations Manager			1995 University Ave., Suite 390
brent at capmkt.com				Berkeley, CA  94704
{cogsci,lll-tis,uunet}!capmkt!brent		Phone:  415/540-6400