Directory Server with huge memory - performance issue

Question

Hi.
We're using Sun Java System Directory Server 5.2Patch6 on Sun T5240
(UltraSPARC T2) with 64GB memory. Setting DBCache + EntryCache > 20G,
some performance degradation occurred.
(A) Sometimes, ping(ICMP echo/reply) reply time was delayed
(from same network segments, it occasionally becomes response time > 100ms
though time is almost response time < 1ms usually).
(B) Small freeze (OS? SDS?) occrred. LDAP search(from other clients)
response time was delayed(access log's etime was <1, but in my experience,
it was delayed).
I've read follwing article.
http://wikis.sun.com/display/SunJavaSystem/Directory+Server+Cache+Sizing
In this article, suggested pagesize tuning. But using pmap command,
ns-slapd was already using 4M page, and using "ppgsz -o heap=256M",
ns-slapd still using 4M page.
So, I have 2 questions.
(1) How to change pagesize using ns-slapd? I want to use 256M pagesize
(supported by Solaris10 / T5240)
(2) Is the above-mentioned problems, due to pagesize?
Regards,
Nokamoto

Answer 1

Setting DBCache + EntryCache > 20G, some performance degradation occurred.Based on real-world observations, memory consumption of directory server can be upto thrice the configured entry cache size plus db cache size. So we can expect your process size to be inching toward your physical memory limit.This would in turn most likely cause a performance degradation as other processes also need RAM and the OS would start paging to disk.
Do you need to increase cache to 20GB?