Swapping and vm on red hat

[Yard, John]

I maintain a Red Hat system 3.2.47 with 12G
of physical memory. The application is 
Sun Directory server 5.2 .

My memory parms are :

[xxxx:/proc/sys/vm] # cat bdflush
50      500     0       0       500     3000    80      50      0
[eds1:/proc/sys/vm] # cat pagecache
1       15      30

I am surprised that with this much memory 
I am slowing using more and more swap space :

The system has bben in production only a week ,
yet I see ;

ds1:/proc/sys/vm] # vmstat 1 5
procs                      memory      swap          io     system
cpu
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy
wa id
 0  0   5436 120196 166200 10942208    0    0     6     8    1     9  2
0  0 11
 0  0   5436 120192 166200 10942208    0    0     0     0  374   584  1
0  0 99
 1  0   5436 120128 166200 10942272    0    0     0     0  678  1295  4
0  0 96
 

with swap space usage slowly growing.

Most of the memory is taken up with file pages,
( very intensive loggin g ),
not program pages.

How do I get the system to preferentially
write back to diak file pages ?

JYard
UCLA