BUFFERS & RA_PAGES
In the performance tuning manual for OnLine 7.x, Informix recommends that
you set your buffers to 25/20% of physical memory. My question is, what unit
are we meant to be measuring memory in. I have presumed kilobytes, so that
for my box with 64 Mb, my buffers are set to 16000. If this is correct then
the formula for RA_PAGES :
RA_PAGES = (BUFFERS * 0.75) / (2 * 12) + 2
yields an RA_PAGES value of 502. I only have six active users and a number
of background processes so I am presuming that 12 is an OK number for 'large
queries'. The problem is that users are complaining that reads of small
queries are taking to long. Included below are the server details, I would
really appreciate any help, and would like to thank Neil Truby and Steve
Drotar for their responses to a previous posting.
Regards
Jon Ridgway
The Press Association
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64 MB memory.
onstat -p :
INFORMIX-OnLine Version 7.11.UC1 -- On-Line -- Up 2 days 18:50:51 --
52320 Kbytes Profile
dskreads pagreads bufreads %cached dskwrits pagwrits bufwrits %cached
434990 1085493 46760648 99.07 85497 108554 244762 65.07
isamtot open start read write rewrite delete commit
rollbk
23504296 606303 2717001 17385932 30175 96833 5207 31812 13
ovlock ovuserthread ovbuff usercpu syscpu numckpts flushes
0 0 0 10153.79 1439.75 393 1606
bufwaits lokwaits lockreqs deadlks dltouts ckpwaits compress seqscans
43447 0 104744513 0 0 89 7808 9389
ixda-RA idx-RA da-RA RA-pgsused lchwaits
95699 10872 74624 152471 26449
------------------
onconfig (edited):
RESIDENT 0
MULTIPROCESSOR 0
NUMCPUVPS 1
SINGLE_CPU_VP 1
LOCKS 6400
BUFFERS 16000
PHYSBUFF 32
LOGBUFF 32LOGSMAX 16
CLEANERS 1
SHMBASE 0xa000000
SHMVIRTSIZE 8000
SHMADD 8192
SHMTOTAL 0
CKPTINTVL 600
LRUS 8
LRU_MAX_DIRTY 60
LRU_MIN_DIRTY 50
RA_PAGES 502
RA_THRESHOLD 498