DEC RA60 Partition Sizes on 4.1BSD

[Chris Torek]

In article <413 at ms3.UUCP> msitd02 at ms3.UUCP (Larry Johnson, ISN-HIOS
Prog. Dir.) writes:
>I ... cannot determin[e] what the size of the last partition (/dev/ra1h)
>should be for the /etc/mkfs "size" parameter.  The driver specifies "-1",
>which the comments say means "to the end of the disk".  

>Please E-mail responses.

I am going to ignore this last directive, for what I hope will soon
be obvious reasons.

According to the 4.3BSD-beta disktab, an RA60 has 42 sectors per
track, 4 tracks per cylinder, and 2382 cylinders, giving a total
of 400176 sectors.  Having no RA60s, I cannot vouch for the accuracy
of this information.  I can, however, show several ways to determine
this yourself.

A partition table `size' of `-1' does indeed mean `to the end of
the disk' in the UDA50/MSCP driver.  The MSCP protocol provides disk
drive size information back to the driver.  This information is
stored (in the distributed drivers) in an array called `radsize'.
You can examine the size of any RA disk once it has been brought
on line.  To force the drive on line, first read one sector from any
partition:

	# assuming you want to examine RA drive #3
	# (which is not necessarily *unit* 3)
	dd if=/dev/rra3a of=/dev/null bs=512 count=1

Now examine the corresponding `radsize' entry:

	adb /vmunix /dev/kmem
	radsize+0t12/D

Here the corresponding entry is radsize[3], which is at _radsize+12,
12 being 3*sizeof(radsize[0]).  (The `0t' tells adb that the
following number is in decimal radix.)

What I do not understand is why the original author of the UDA50/RAxx
driver did not print the disk size information.  This will come in
quite handy when (if?) DEC releases the RA82, since no one will
yet have accurate information for the drive, and requiring the use
of adb to find the size can, at best, be called `arcane'.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1516)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris at umcp-cs		ARPA:	chris at mimsy.umd.edu