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RE: Speeding up BDB question

First I want to make a correction:  The openldap version is 2.4.22, I
had a typo.

> -----Original Message-----
> From: Christian Kratzer [mailto:ck-lists@cksoft.de]
> Sent: Tuesday, April 05, 2011 5:53 AM
> To: Quanah Gibson-Mount
> Cc: Cannady, Mike; openldap-technical@openldap.org
> Subject: Re: Speeding up BDB question
> Hi,
> On Mon, 4 Apr 2011, Quanah Gibson-Mount wrote:
> >
> >
> > --On April 4, 2011 3:12:40 PM -0400 "Cannady, Mike"
> <mike.cannady@htcinc.net>
> > wrote:
> >
> >> I have a situation where I need to delete a major branch of my DIT
> >> reload it with a new ldif file on live systems.  My current
> >> configuration is a two node multi-master running on Red Hat
> >> 5.4 with openldap 2.22 and BDB 4.8.26.
> >
> > I strongly advise using a later version of OpenLDAP for a variety of
> reasons.

I would like to do that but I have issues with uptime and the two-node
multi-master with readonly replicates off the masters that I'll address
in another post.  

> > That aside, why not use a shared memory key for the BDB backing
> instead
> > of putting it on disk?
> propably because most people and packagers just default to berkeley db
> file
> based caching and the sysv shared memory caching is largely unknown.
> Perhaps this sould be featured more in the documentaion.

I agree.  I saw no hint of using sysv shared memory anywhere in the
openldap FAQ.  I assume that "DB_SYSTEM_MEM" would have to be in the
DB_CONFIG file and "dbconfig set_flags DB_SYSTEM_MEM" in slapd.conf to
cover a new database.  Is this correct?  

> > Finally, RAM will always be faster than disk.  If your database is
> properly
> > configured via the threads, entry cachesize, the idl cachesize, the
> > checkpoint frequency, and the BDB DB_CONFIG configuration for locks,
> lockers,
> > and DB cachesize, then there's probably not much more you can do.
> >
> > Of course, you don't provide any data that lets us know whether or
> the
> > settings you showed are valid.  I.e., you don't state the number of
> in
> > the database, or the size of the database, or any of your stats from
> > database.
> I have seen performance get exponentially worse on linux with the
> fsync changes that came somewhere after the 2.6.18 kernels.
> on linux has never been fully restored with later kernels.
> Greetings
> Christian

I used the ram filesystem to see if there was a lot of filesystem
flushing via some kind of sync.  The I/Os I saw just didn't seem right
for the amount of changes happening every minute.

As to the database size and such:  The ldapadd was adding 51,265 DNs
back into the ldap store.  The preceding delete was close to that number
also.  The database before any of the operations had 71,886 DNs

> --
> Christian Kratzer                      CK Software GmbH
> Email:   ck@cksoft.de                  Wildberger Weg 24/2
> Phone:   +49 7032 893 997 - 0          D-71126 Gaeufelden
> Fax:     +49 7032 893 997 - 9          HRB 245288, Amtsgericht
> Web:     http://www.cksoft.de/         Geschaeftsfuehrer: Christian
> Kratzer

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