[Fedora-directory-users] Advantages of using FDS vs OpenLDAP?

[Kevin Myer]

Quoting Mike Jackson <mj at sci.fi>:

> Hi Pierangelo,
>  The fact that LDAP directory servers are not intended to support a 
> high frequency of write operations means that the term "write load 
> balancer" is not the correct term to use when describing the benefits 
> of multi-master versus single-master replication - unless you are 
> arguing how to support systems architects who intentionally (or 
> perhaps out of ignorance) use LDAP technology in an incorrect manner 
> in their designs. The correct term to use in this context, IMO, is 
> "highly available write operations".

I thought that more accurately describes it as well.  And my approach would be
to have a "primary" master and a "secondary" master.  Throw all your writes at
your primary master and if they all go through there, no need to worry about
consistency.  In the event of a disaster, the secondary master is quite 
capable
of taking the writes as well and keeping things running.  This is almost akin
to your master/promotable slave concept, except the promotable slave is not
really a slave but a standby master.  If you're concerned about load, throw in
a bunch of slaves that are read-only and point your read-only lookups at the
slaves, reserving your masters for applications that need write access.

End result - highly available write operations, that minimize consistency
issues.  Highly available read operations.  It requires intelligent 
design of a
directory infrastructure, as you note - sometimes I think we expect 
software to
design that too :)

Kevin

-- 
Kevin M. Myer
Senior Systems Administrator
Lancaster-Lebanon Intermediate Unit 13  http://www.iu13.org