Problems installing a CDC WREN V on a SUN.

[Michael J. MacDonald I.S.P.]

  We are trying to install a CDC WREN V 94181-702 on our SUN4 running
 SUNOS 4.0.3.

  I am trying to figure out the disk geometery to make sure that we do
  not have overlapping partitions on the disk.

  The spec sheet on the drive states
   Model       Number of cyls  number of data heads
 94181-702         1546              15

 The description of the drive that comes from sun is
#
# @(#)format.dat 1.15 90/02/02 SMI
#
# Copyright (c) 1987 by Sun Microsystems, Inc.
 (stuff deleted )
disk_type = "CDC Wren V 94181-702" \
 	: ctlr = MD21 : fmt_time = 4 \
 	: cache = 0x11 : trks_zone = 15 : asect = 2 \
 	: ncyl = 1543 : acyl = 2 : pcyl = 1545 : nhead = 15 : nsect = 48 \
 	: rpm = 3592 : bpt = 33408
 (stuff deleted )
#
# Following is a list of sample partition tables for embedded SCSI disks.
#
partition = "CDC Wren V 94181-702" \
 	: disk = "CDC Wren V 94181-702" : ctlr = MD21 \
 	: a = 0, 32025 : b = 61, 59850 : c = 0, 639450 : g = 175, 547575
 (stuff deleted )


 After installing the drive running format gives:

  Searching for disks...done

  AVAILABLE DISK SELECTIONS
     0. sd0 at sw0 slave 0
        sd0: <Micropolis 1558 cyo 1218 alt 2 hd 15 sec 35>
     1. sd2 at sw0 slave 8
        sd2: <CDC Wren V 94181-702 cyl 1547 alt 2 hd 15 sec 48>
     2. sd4 at sw0 slave 16
        sd4: <CDC 94181-702-2 cyl 1547 alt 2 hd 15 sec 50>

    Disk sd0 is the original from sun (no problems)
    Disk sd2 is a third party disk, (the brand new disk)
    Disk sd4 is a third party disk, also having problems (I will get to that
    later).

    Disk sd2 and sd4 are ``identical'', They are both 94181-702s.

    It appears to me that I have three opinions of the number of cyls
    on the disk. One from the spec sheet, one from the format.dat and
    one that appears to come from the disk label.

    Also there seems to be either 48 or 50 sectors per track.
     Question 1: Any guesses as to how many real cylinders are on the disk?
     or any guesses as to how many real sectors per track on the disk?

     The next problem I have is how to I calculate the partition
     sizes so that there are no overlaps.

     Question 2: Is there always the same number of sectors per track
     regardless of the cylinder of the track. Does cyl 0 have the
     same number of sectors as cyl 1500? I always thought it was constant
     but I was assured by an EE that there were more sectors on cyl 0 than cyl
     1500.


     If I use format to print the partition table I get the following

      sd4:(the ``old'' drive)
       partition a - starting cyl    0, #blocks  580125 (773/7/25)
       partition b - starting cyl  773, #blocks  580125 (773/7/25)
       partition c - starting cyl    0, #blocks 1160250 (1547/0/0)
       (all others 0).
     This drive appears to have  sd4a and sd4b overlapped.

           step 1: sd4a ok, sd4b bad filesystem
                   fsck sd4b
           step 2: sd4a bad filesystem, sd4b ok
                   fsck sd4a  (go to step 1)

   Question 3: if partition b starts at cyl 773 is that the very beginning
               of cyl 773.
               If the 773/7/25 means that the first 7 tracks and 25 sectors
               are used by partion a. I take it this means part a and part b
               are overlapped on one another.

    Does anyone have a correct format.dat entry for this disk?
    What about an example or two of valid partition tables?
    It states in the ``Systems Administration Procedures'' that I am
    supposed to leave 4 cyls free for use by the MD21 controller.
    See page 188. Pcyl entry
    It says ``Pcyl - must be assigned the number of physical cylinders
    in the disk type. This number is used to calculate the boundaries
    of the disk media. This number is usually equal to ncyl plus acyl,
    but there are some circumstants under which it is not. For instance
    the Emulex MD21 controller requires four cylinders for internal use,
    so they must be left off the other assignments. ...''

    Where is this taken into account in  the above tables?

     I'm confused.
        HELP.

     Mike

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 Michael MacDonald, I.S.P.                              /||\
 Senior Systems Specialist,                           /  || \
 Faculty of Computer Science                        /    ||  \
 University of New Brunswick                      /      ||   \
 Po. Box 4400                                   /        ||    \
 Fredericton, New Brunswick                   /          ||      \
 CANADA    E3B 5A3                          /            ||       \
                                          <______________||________>
 (506) 453-4566                          ________________||___________
                                       / ___________________________/
 Netnorth/BITNET: MIKEMAC at UNB.CA      /_/    I'd rather be sailing.

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