[TUHS] System V Release 2, adding swap?

Charles H. Sauer sauer at technologists.com
Wed Jan 27 02:46:56 AEST 2021

On 1/26/2021 10:05 AM, Henry Bent wrote:
> On Mon, 25 Jan 2021 at 11:02, Arnold Robbins <arnold at skeeve.com 
> <mailto:arnold at skeeve.com>> wrote:
>     Hi.
>     Does anyone know how to add swap space on a System V Release 2 system?
>     In particular, on an emulated AT&T 3B1. The kernel is S5R1 or S5R2
>     vintage.
>     I don't see any commands with 'swap' in their names.
> A little bit of Google Groups trawling turned up this: 
> https://groups.google.com/g/comp.sys.att/c/8XLILI3K8-Y/m/VxVMJNdt9NQJ 
> <https://groups.google.com/g/comp.sys.att/c/8XLILI3K8-Y/m/VxVMJNdt9NQJ>
> But I don't have one of those systems, so I have no way to verify.
> -Henry

I don't know about 3B versions, but on Dell SVR4 on 86Box 
I see
/ # apropos swap
swap(1m): swap - swap administrative interface
swapctl(2): swapctl - manage swap space

I've never tried to adjust swap, just trust that our install did the 
right thing. On this system, freshly booted, with 32M memory and 5G 
"disk", I see
/ # swap -l
path                 dev  swaplo blocks   free
/dev/swap            0,2       0  98784  90960

Here's the beginning of man swap:
      swap - swap administrative interface

      /usr/sbin/swap -a swapname swaplow swaplen
      /usr/sbin/swap -d swapname swaplow
      /usr/sbin/swap -l [ -s ]
      /usr/sbin/swap -s

      swap provides a method of adding, deleting, and monitoring the  system
      swap  areas  used  by  the  memory manager.  The following options are

      -a   Add the specified swap area.  swapname is the name of  the  block
           special partition, e.g., /dev/dsk/0s2 or a regular file.  swaplow
           is the offset in 512-byte blocks into  the  partition  where  the
           swap  area  should begin.  swaplen is the length of the swap area
           in 512-byte blocks.  This option can only be used by  the  super-
           user.   If  additional  swap areas are added, it is normally done
           during the system start up routine  /etc/rc2.d  when  going  into
           multi-user mode.

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