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RE: HDB Tuning
--On Thursday, January 18, 2007 9:32 AM +0900 Mark Mcdonald
From: Buchan Milne [mailto:email@example.com]
Sent: Thursday, January 18, 2007 12:17 AM
Is there any reason you didn't include BDB as well ?
We have a reasonably high write component in our system so we thought
we'd go straight for HDB. From my fairly limited reading, I get the
impression that HDB >= BDB, although I've seen nothing criticising HDB
comparative to BDB. Is it something we should also consider? For what
BDB and HDB are generally equivalent in search rates, IIRC. I haven't done
a direct comparison in a while though. However, I switched to using HDB on
my servers and they've been quite responsive.
How many entries in the database, or how large is it (du *.bdb) ?
1.3GB, 800k entries in one database. No glue or other overlays.
Really, the important part is, how large is id2entry. You generally want
your DB_CONFIG database cachesize to be id2entry + at least 10% for growth.
For loading the database via slapadd, you want the size of *.bdb. So I
generally just set it to the latter number.
I think you need (more?) idlcache, configured in slapd.conf inside the
database. And, if you don't have any, you also need a cachesize
configured (in the same place). See the man page for slapd-hdb (or
slapd-bdb). IIRC the
guideline for idlcache on hdb is approx three times the cachesize (which
will have to decide on).
Bingo! Adding the idlcachesize made a world of difference, thanks! I
didn't check that man page so never realised the index caching config
directive had changed. I've followed the 3x rule and it's super-speedy
Yeah, the man pages are important. :)
Principal Software Developer
ITS/Shared Application Services
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