Ultrix-11

[Warner Losh]

On Fri, Aug 20, 2021 at 9:50 AM Peter Allan via cctalk <
cctalk at classiccmp.org> wrote:

> How can I make a larger /usr partition? Is it possible to do this at
> installation time? There did not seem to be an option for this. Can it be
> done by using an additional disk? That would seem likely, but not what a
> system manager back in the 70's or 80's would expect to need to do,
> especially as there is a relatively large amount of space left to create
> /user1.
>

Ultrix-11 is old-school Unix. This means that it uses hard-wired partitions.

It's based on the controller that you use. So for an RD54 connected to an
RQDX3 would use the rq_sizes entry from dksizes.c:

/*



 * Sizes for RD31/RD32/RD51/RD52/RD53/RD54/RX50/RX33 disks.



 */
struct  rasize  rq_sizes[8] = { /* RQDX1/RQDX2/RQDX3/RUX1 */
        9700,   0,              /* RD31-32,51-54 root (swap+error log -
rd51) */
        17300,  9700,           /* RD32/RD52/RD53/RD54 /usr */
        3100,   27000,          /* RD32/RD52/RD53/RD54 swap + error log */
        -2,     30100,          /* RD32/RD52/RD53/RD54 user files */
        -2,     9700,           /* RD51 /usr */
        3100,   9700,           /* RD31 swap + error log */
        -2,     12800,          /* RD31 /usr */
        -1,     0,              /* RD31-32, RD51-54 entire disk */
};

 *      Note    - nblocks has two values with special meaning:



 *



 *                An nblocks value of -1 specifies a partition length of



 *                the size of the entire disk minus the partition's
starting


 *                block number. In other words, the partition ends at the



 *                end of the disk.



 *



 *                An nblocks value of -2 specifies a partition length of



 *                the size of the disk minus the size of the maintenance



 *                area minus the starting block number of the partition.



 *                In other words, the partition ends at the start of the



 *                maintenance area.




So a RD-54 is

 *              RD54



 *      +-----------------------+



 *      | 0   9700  root        |



 *      |                       |



 *      +-----------------------+



 *      | 1  17300  /usr        |



 *      |                       |



 *      |                       |



 *      +-----------------------+



 *      | 2    100  error log   |



 *      |     3000  swap        |



 *      +-----------------------+



 *      | 3 281068  user        |



 *      |                       |



 *      |                       |



 *      |                       |



 *      +-----------------------+



 *      | 32 maintenance area   |



 *      +-----------------------+



 *        7  311200  (user = 311168)



 *

and that's what you get. You could change the rq_sizes array, but that's
tricky to set up...

It's a lot easier to use a RA81 instead. It's 450MB instead of the 150MB
the RD54 in the
example and gives plenty of room.

You could also use a RA80 instead. It's a little smaller than the RD54 at
120MB, but it
as a 20,000 block /usr instead of the kinda tiny 17,200 block area of the
RD54. The RA60
is also an option at 200MB with the same 10MB /usr.

Warner

P.S. Kudos to the anonymous DEC employee that drew all the pictures for
each of
the supported disks in dksizes.