Re: High availability

[Howard Chu <hyc@symas.com>]

Taymour A. El Erian wrote:
> Dmitriy Kirhlarov wrote:
> > Taymour A. El Erian wrote:
> > > Hi,
> > >
> > > I have been searching for a long time to find a solution to give me 
> > > high availability on the writing. We have 2 ldap servers running as 
> > > multi master (I know it is not considered a good thing and it is very 
> > > old 2.0.x), this way if one is down the other will accept writes 
> > > (add/modify/delete). If we do the normal single master multiple 
> > > slaves, we will get more performance and high availability for reads 
> > > but if the master is down no updates. Also, we can not separate 
> > > writes from reads and we can not use referrals (not all applications 
> > > we have can chase referrals). I though of having a standby master and 
> > > use heartbeat but it doesnt look like a stable solution, any ideas ? 
> > > maybe shared disk ?
> > For openldap 2.{2,3}.x you can use ggated+gmirror+carp (on freebsd) or 
> > heartbeat + mirror with drdb (on linux). It should work.
> >
> > For openldap 2.4 two-node multi-master solution declared, afaik, but 
> > currently 2.4 is alpha.

Two-node high availability support was in older 2.4 alpha releases. Current 2.4 
releases support full N-way multimaster.

> Thanks dmitriy, Would you happen to have any documentation regarding 
> Linux. What about the case I explained, that we have clients that do 
> read/write, how to send the writes to the masters and reads to slaves 
> without having the clients chase referrals ?

Use the chaining overlay. See test017 for an example configuration.
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP     http://www.openldap.org/project/