ct_sql vs. ct_shm

[moorewr@eckerd.edu]

We are running IMP on a dedicated Dell linux box - a PIII/866
with 512mb. It has Horde/IMP 1.2.4/2,4 (because, as I noted
previously, 2.5 has a large compose/prefs bug under this
config), postgres 7.03, RH 7.1, and php-4.0.4pl1-9. We get
30-50,000 hits on the server each day.

We have found that even with vacuuming, etc, it seems unable to
keep up with requests if we use postgresql for session
managment. Eventually the load on the system will soar up beyond
30 and the system cracks, even though the CPU is idle.

As a workaround (for our angry college president) we switched to
SHM session management. This is lightning fast, HOWEVER, after n
# of hours it eats up all the available shared mem. I've set the
size of the shm segment higher and higher - from 64000 to
99900000. Eventually the server stops returning requests and I
have to restart httpd.

We've tweaked various parameters - php/imp session max time,
KeepAlive, etc, without much variation in these problems.

Anyone have any inspiration for me?

Thank you..

+------------------------------------------------------------
Walter R. Moore --  System Administrator, Eckerd College
moorewr@eckerd.edu --  http://www.eckerd.edu/~moorewr

"Nothing in the UFO phenomena, the fundamentalist complaint
goes, requires belief in the one, true God, while much in it
contradicts th God portrayed in the Bible and Christian
tradition. _The New Age: A Christian Critique_ by Ralph Rath
discusses UFOs -- typically for such literature, with extreme
credulity. It serves their purpose to accept UFOs as real and
revile them as instruments of Satan and the Antichrist, rather
than to use the blade of scientific skepticism. That tool, once
honed, might accomplish more than just a limited heresiotomy."
	- Carl Sagan _The Demon-Haunted World_

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