Embedded SCSI disks

[Dave Kemp]

We just received two Hitachi DK515C-78 disks (660 MB, 16ms) and are using
them with 3/60's running 4.0.1.  They were apparently pre-formatted by
Hitachi, and the vendor (who shall remain nameless for now) claims that
they are permanently formatted, i.e.  they cannot be formatted by software
and nothing can possibly cause them to become unformatted.  Since we have
lost data on Sun 327's after power power failures, I worry that the same
thing could render the Hitachi's permanently unusable.

I have added the following entry to /etc/format.dat:

 disk_type = "Hitachi DK515C-78" \
    : ctlr = MD21 : fmt_time = 1 \
    : ncyl = 1353 : acyl = 2 : pcyl = 1361 : nhead = 14 : nsect = 69 \
    : rpm = 3600 : bpt = 40936

along with an appropriate partition entry.  When I try to format the
disk, I get:

  Warning: using default mode select parameters.
  Warning: Drive format may not be correct.
  Block 3 (0/0/3), Fatal non-media error (illegal request)
  failed

The Sun hotline engineer (who got back to me the day after I logged the
call) said the illegal request message occurs only in the subroutine for
the Adaptec controller, but since the disk isn't supported he couldn't
help me any further.  That is very puzzling since the Emulex MD21
controller is specified in format.dat.  The two warnings aren't documented
anywhere, and Sun couldn't tell me anything about them.  Does anyone have
any comments on the following:

 1) Is it possible that this disk does indeed have some form of hard
sectoring?  It seems unlikely to me.

 2) Can the SunOS 4.0.1 format program be coerced into working with this
drive?  Have you worked with this or other embedded SCSI disks?

I really like the drives; they are in a small cabinet, they are extremely
quiet, and they have the disk activity light out where I can see it!  The
small amount of abuse I gave them (pulling the plug while they were
writing) didn't cause any damage that fsck couldn't fix.  They work fine
with everything else (surface analysis, defect list management) and we are
booting from them with no problems.  But I don't want to accept them (or
buy any more) if there is a chance that they can become unformatted and I
can't fix them.

Thanks for any insight.

  Dave Kemp <Kemp at dockmaster.ncsc.mil>