Re: dbcachenowsync

[kunkee@neosoft.com (Randy Kunkee)]

> Randy,
> 
> I saw your posting and had a question about dbcachenowsync.
> 
> I have been testing OpenLDAP 1.2.x with this option enabled to increase
> write performance.  However, I have observed the id2entry.dbb file
> increasing as more data is added to LDAP.  In addition, restarting the
> machine does not cause LDAP to loose any data.
> 
> My question is this:  When dbcachenowsync is enabled, is slapd never
> synchronizing data to disk or is it just doing it less frequently.
> 
> Thanks,
> Mark
> 

If you mean restarting the machine after a crash, you are either lucky,
or you have been unlucky and you just don't know it yet.

If you have a lot of search/read activity, you will be getting some
flushes as time goes on.  The more likely symptoms (in the event
of a slapd or system crash) will be that one of the index files
doesn't get flushed, and an object searched by filter does not
appear even though a base search exists.

My application has lots of write activity, and lots more searches
going on.  I survived for quite some time without many problems,
even with slapd crashing.  That's a testament to Sleepycat DB's
ability to keep the database files consistent (within themselves).
Finally, I write a sync_daemon() thread to address my particular
needs.

If, by restarting the machine, you are including a normal shutdown,
then slapd will be sent the signals it needs to tell it to shut down
and correctly flush everything it hasn't yet flushed.