Re: a few back-bdb tuning questions

[Quanah Gibson-Mount <quanah@stanford.edu>]

Quoting matthew sporleder <msporleder@gmail.com>:

> I am using openldap 2.3.21 and bdb 4.4.20 (both compiled 64-bit) on
> solaris 10.
>
> I followed (How do I determine the proper BDB/HDB database cache
> size?) http://www.openldap.org/faq/data/cache/1075.html and saw the
> note:
> "I don't have enough free RAM to hold all the 800MB id2entry data, so
> 4MB is good enough."
> And I found my number (around 30MB), which got me -great- read
> performance.
>
> (so far I have my sun v120 upto 750+ BINDS/second using slamd and a
> few thousand test accounts.  Although, when I turned on logging, it
> went down to 350/second)

This seems rather low.  I'll note that on Solaris it is best to use a shared
memory cache.  My SunFire 120's get several thousand searches/second.

> Well.. what if you do have enough ram?  Do you just set a huge cache
> size, and it will eventually grab the whole thing?  Do I need to
> include my indexes and other things in that memory calculation, or
> just the id2entry?

Yep.

> The man page mentions that hdb needs a very large idlcachesize
> relative to the cachesize.  What's the bdb recommendation on this?
>
> When I checkpoint and use DB_LOG_AUTOREMOVE, what am I losing?  The
> old transactions that have already been written to the database on
> disk?  This would mean that my log.### are all active, correct?  Since
> the old ones would have been deleted.
>
> And can multiple subordinate databases (I didn't find a lot of
> documentation about subordinate, by the way.  Shouldn't that be in
> slapd.conf(5)?) share the same set_lg_dir?  Or should they be
> separated into directories of their own?

Their own directories with their own DB_CONFIG files.

I suggest reading over:

http://www.stanford.edu/services/directory/openldap/configuration/

--Quanah