RE: High Availability / Clustering

["Howard Chu" <hyc@highlandsun.com>]

> -----Original Message-----
> From: owner-openldap-software@OpenLDAP.org
> [mailto:owner-openldap-software@OpenLDAP.org]On Behalf Of Lee

> Ive read through most of the archives concerning high-availability
> options for openldap. Right now, we're trying to create make our ldap
> infrastructure highly-available, as well as load-balanced
> between three
> servers (more to be added later). From my research it seems like we
> have a few options:
>
> 1) Experimental Multi-Master: This seems to have a number of
> atomicity
> issues. Plus this doesn't really solve the problem with the ldap
> clients not appropriately using the second listed server if the first
> goes down.

Any load-balancing front-end should handle the latter problem. I won't bother
rehashing the rest.

> 4) 1 Master Server Cluster using shared storage: This seems like the
> only viable solutions.

If you honestly believe this, then your definition of "high availability" is
somewhat different from the rest of the world's. Putting a bunch of front
ends onto a single shared data-store does not give high availability. It
practically assures lower availability, because your shared storage is now a
single point of failure. If it goes down, it doesn't matter how many servers
are in your cluster, they're all hosed. This idea is pure folly. There are of
course valid reasons for using tightly coupled server clusters with shared
storage, but high availabilty is definitely not one of them.

  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support