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RE: LDAP/BDB log purging

--On Thursday, March 01, 2007 10:48 AM +1300 Lesley Walker <lesley.walker@opus.co.nz> wrote:

Buchan Milne [mailto:bgmilne@obsidian.co.za]
> Well, I just ran db_archive and caused widespread chaos
because most (all?)
> of the replicas stopped responding to queries. (I have yet
to perform a
> post-mortem)

You ran db_archive for the first time, on *all* replicas at
the same time????

Yes. We administer 80+ servers that are more or less identically configured, and typically perform small admin tasks in "for" loop, which is what I did in this case.

> I know that there's a bug in bdb 4.2 that causes logs to be
held open even
> though they're no longer required. Upgrading bdb is not on
the cards right
> now so I need to work around that problem by stopping and starting
> openldap.

This may or may not be the cause of your problems.
Additionally, this is
affected by your database configuration and checkpointing settings.

Copied below...

> So the question I have just at the moment is, when I run
db_archive, should
> openldap be running or not running?

It should be safe, depending on your configuration, to run
However, due to the tasks it does (just deleting all the
unused log files
would have a similar effect), it can be quite IO intensive,
and you may incur
IO starvation when doing it, impacting performance of any
other application
using files on the same block devices (e.g. slapd).

As an additional piece of background, we are currently running all the replication out of an intermediate server (it's a transistional setup). As far as I can tell, it all hit the fan when the db_archive ran on that intermediate server. Obviously I should have left that one out of the list but I didn't think of it at the time.

These are all the non-comment entries in DB_CONFIG:

set_cachesize 0 268435456 1
set_data_dir db
set_lg_regionmax 262144
set_lg_bsize 2097152
set_lg_dir logs
set_tmp_dir /tmp

Database definition entries in slapd.conf:

database        bdb
suffix          "dc=example,dc=com"
rootdn          "cn=root,dc=example,dc=com"
rootpw          secret
directory       /var/local/openldap-2.3.32/openldap-data
mode            0600
sizelimit       12000

I see no checkpoint directive for this database. You definitely want that.


-- Quanah Gibson-Mount Principal Software Developer ITS/Shared Application Services Stanford University GnuPG Public Key: http://www.stanford.edu/~quanah/pgp.html