AIX 3.1 paging space

[David H Close]

Recently Matt Landau (mlandau at bbn.com) wrote:

" Increasing paging space from 60 MB to 120 MB made that problem disappear.
" Yes, that's 120 MB of paging space, to create a 7 MB binary image.  Why
" it takes so much, I'll never understand, but needless to say we won't be
" trying it on a 320 with a 120 MB disk :-)

I have been trying to make perl 3.28 on AIX 3.1.  Using a 320 with about 400
MB of disk total.  34 MB paging space with 16 MB RAM.  It dies compiling
eval.c, and several others if I bypass that one.  I noticed that when it dies,
the console reports paging space is low.  So I investigated.

Immediately after booting, with only root logged-in on the hft, smit reports
that paging space is about 50% used!  How can this be?  There is no obvious
reason for any paging to have occured at that time.  During normal operation,
we have up to six X terminals running, each with 2 or 3 windows.  smit will
usually show paging space over 80%.  Not much of an increase over the fairly
quiescent state right after boot.

When originally installing, I took the default paging space of 32 MB, not
knowing better.  Later I found only an extra 2 MB available to extend it.
The space is divided between two disks, in logical volumes hdisk6 and hdisk61.
AIX doesn't seem to efficiently use the two areas, reporting problems while
hdisk61 is still below 50% used.  Is this normal?

This problem is getting serious enough that I would back-up and re-allocate
the logical volumes.  Except that the 320 is supposed to be replaced with
a 520 "any day".  And I need the user space.  Should I really plan to
allocate 120 MB paging space on the 520? !!!  That seems totally unreasonable.

Dave Close, Compata, Arlington, Texas
compata at cup.portal.com
compata at mcimail.com