Swap on 4.2 BSD

[danl at midget.towson.edu]

Tim Evans <tkevans at fallst.uucp> writes:
>11/750's running 4.2 BSD and have been rummaging around on them.  I've
>discovered that, although /etc/rc starts up 'swapon -a' there is no
>swap partition defined in /etc/fstab.

I run Ultrix on VAXen, which is a descendent of BSD, so I'm assuming this
all works the same.  "swapon -a" adds secondary or supplemental swap space
(namely other disk partitions marked :sw: in /etc/fstab and configured into
the kernel) to the primary swap which is also defined in the kernel config
file.  Try looking in /usr/sys/conf/machine_name for something like:

config	vmunix	root on ra0a  swap on ra0b  dumps on ra0b  

The above specifies ra0b as my primary (and only) swap space, and therefore
needs no entry in /etc/fstab.

"swapon -a" is in your /etc/rc in case you want to add other partitions as
swap.  To do this you need to add the parttion to the config file, reconfig
the kernel, add the partition to /etc/fstab, and reboot.  The line:

config	vmunix	root on ra0a  swap on ra0b  swap on ra1b  dumps on ra0b  

specifies ra0b as my primary swap and ra1b as an optional secondary swap
to be added by "swapon -a" if it is in /etc/fstab.

>/etc/disktab's entry for the Eagle disk(s) on the 4 machines appears to
>show a 'b' partition having been defined.

The "b" partition is usually used for swap, so if your system is running and
all you have is the one drive, it is probably already being used.  Try
"pstat -s" to see it's size, and check the config file again for its
location.  You shouldn't take /etc/disktab as gospel though, because it's
values are only default suggestions, and can be over-ridden by chpt.  Try
"chpt -q" to see how the disk is really layed out.

I have two Eagle's on one system and interleave the swap between them.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Dan Gosner				Internet: danl at midget.towson.edu
Operations Manager				  DGosner at TOE.TOWSON.EDU 
Towson State University			Bitnet:   DGosner at TOWSONVX
Academic Computing
Towson, Maryland  21204
   %% VMS pays the bills, but Unix is where my real work gets done. %%