Partitioning during installation

Hello,

I have noticed something strange while installing NetBSD/vax 9.1
onto a MicroVAX simulated using simh. The physical host runs NetBSD/
amd64 and simh-4.0.0.20180919nb2 was built from pkgsrc-2020Q3.

As you will see below, the partition sizes change unexpectedly.
I'm not sure whether this is something in sysinst itself, the disk
driver or a quirk of simh. I get similar results whether I specify
partition sizes in sectors, cylinders or MB.

-Andy Ball

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On which disk do you want to install NetBSD?

,--------------------------,
| Available disks |
| |
|>a: ra0 (1.4G) |
| b: Extended partitioning |
| x: Exit |
`--------------------------'

----------------------------------------------------------------------
You can use a simple editor to set the sizes of the NetBSD partitions, or
apply the default partition sizes and contents.

You will then be given the opportunity to change any of the partition
details.

The NetBSD (or free) part of your disk (ra0) is 1436M.

A full installation requires at least 610M without X and at least 760M if the
X sets are included.

,----------------------------------------------------------------,
| What would you like to do? |
| |
|>a: Set sizes of NetBSD partitions |
| b: Use default partition sizes |
| c: Delete everything, use different partitions (not disklabel) |
| x: Cancel |
`----------------------------------------------------------------'

----------------------------------------------------------------------
You can now change the sizes for the system partitions. The default is to
allocate all the space to the root file system. However, you may wish to
have separate /usr (additional system files), /var (log files etc) or /home
(users' home directories) file systems.

Free space will be added to the partition marked with a '+'.

Size (sec) Filesystem
----------------------------------- - --------------------
>a: 634880 (2678807) + /
b: 262144 <swap>
c: 0 /tmp (mfs)
d: 0 /usr
e: 0 /var
----------------------------------- - --------------------
g: Add a user defined partition
h: Clone external partition(s)
i: Change input units (sectors/cylinders/MB/GB)
x: Go on. Free space 2043927 sec.

----------------------------------------------------------------------
You can now change the sizes for the system partitions. The default is to
allocate all the space to the root file system. However, you may wish to
have separate /usr (additional system files), /var (log files etc) or /home
(us,----------------------------------------------------------------------,
| Choosing mega- or gigabytes will give partition sizes close |
Fre| to your choice, but aligned to cylinder boundaries. |
| Choosing sectors will allow you to more accurately specify |
| the sizes. On most disks, there is little to gain from |
| cylinder alignment. On very old disks, it is most efficient |
| to choose partition sizes that are exact multiples of your actual |
| cylinder size. |
| |
| Choose your size specifier |
| |
| a: Gigabytes |
| b: Megabytes |
|>c: Cylinders |
>| d: Sectors |
`----------------------------------------------------------------------'

----------------------------------------------------------------------
You can now change the sizes for the system partitions. The default is to
allocate all the space to the root file system. However, you may wish to
have separate /usr (additional system files), /var (log files etc) or /home
(users' home directories) file systems.

Free space will be added to the partition marked with a '+'.

Size (cyl) Filesystem
----------------------------------- - --------------------
a: 668 (2822) + /
b: 276 <swap>
c: 0 /tmp (mfs)
d: 0 /usr
e: 0 /var
----------------------------------- - --------------------
g: Add a user defined partition
h: Clone external partition(s)
>i: Change input units (sectors/cylinders/MB/GB)
x: Go on. Free space 2153 cyl.

----------------------------------------------------------------------
Size (cyl) Filesystem
----------------------------------- - --------------------
>a: 146 /
b: 276 <swap>
c: 0 /tmp (mfs)
d: 0 /usr
e: 0 /var
----------------------------------- - --------------------
g: Add a user defined partition
h: Clone external partition(s)
i: Change input units (sectors/cylinders/MB/GB)
x: Go on. Free space 2676 cyl.

----------------------------------------------------------------------
Size (cyl) Filesystem
----------------------------------- - --------------------
a: 146 /
>b: 292 <swap>
c: 0 /tmp (mfs)
d: 0 /usr
e: 0 /var
----------------------------------- - --------------------
g: Add a user defined partition
h: Clone external partition(s)
i: Change input units (sectors/cylinders/MB/GB)
x: Go on. Free space 2661 cyl.

----------------------------------------------------------------------
Size (cyl) Filesystem
----------------------------------- - --------------------
a: 18446744073709550791 /
b: 292 <swap>
c: 0 /tmp (mfs)
>d: 2841 /usr
e: 0 /var
----------------------------------- - --------------------
g: Add a user defined partition
h: Clone external partition(s)
i: Change input units (sectors/cylinders/MB/GB)
x: Go on. Free space 791 cyl.

----------------------------------------------------------------------