Application Development Software

This issue has also been submitted to iPlanet support.

In NSMS 4.15 p6, Solaris 2.6, two IMAP daemons, two mshttpd daemons:

I am trying to get a better understanding of password caching. See service.authcachettl and service.authcachesize in the NSMS tuning guide.

The guide says "The authentication cache ... is not shared between different processes". It also says "Its value should be greater than or equal to the number of users who have their mailbox on the machine to avoid pushing entries out of the cache before the TTLs expire."

Our user population is about 60% webmail, 40% IMAP. I turned logging for each of these to Debug level to see the password caching numbers. Here is a log entry for each of our four processes:

HTTP:
httpd[3568]: General Debug: Password cache: 7344 entries, 20635 hits, 57565 misses, 22651 collisions.
httpd[3564]: General Debug: Password cache: 7255 entries, 20573 hits, 57327 misses, 21798 collisions.

IMAP:
imapd[3515]: General Debug: Password cache: 4109 entries, 250843 hits, 73057 misses, 16132 collisions.
imapd[3522]: General Debug: Password cache: 4120 entries, 252521 hits, 93979 misses, 16582 collisions.

We have approximately 20,000 mailboxes so I set the cache size somewhat higher than that, but it appears that each daemon only needs around 5 to 10 thousand. Is that a setting for each process as is implied by the tuning guide? If so, why so they suggest setting it at the number of mailboxes? Does each process have to allocate memory for the auth cache at startup? Am I wasting memory?

Other questions I have:
What are collisions?
What are some possible explanations for such a poor hit to miss ratio in http?
From what time are these numbers? That is, is there any time at which they reset without restarting services?

Thanks.

Mark Evangelista
Georgetown University
Washington, DC, US