Re: Multiple suffixes per server

[Howard Chu <hyc@symas.com>]

Dave Horsfall wrote:

> I don't think that is possible with OpenLDAP, but I'm willing to be 
> convinced otherwise; I've also been told that this called 
> "multi-mastering", but I know that that's the wrong term.
>  
The realm of possibility is far greater than any one person can imagine...

> Let's say that BigCorp.com (dc=BigCorp,dc=com) has just been taken over by 
> Cobber.com.au (dc=Cobber,dc=com,dc=au).  As is the wont of ways like this, 
> both need to retain their corporate identities despite the hierarchy, with 
> the possibility of having the directory available to the public.
>
> In other words, I need to serve "dc=BigCorp,dc=com" and 
> "dc=Cobber,dc=com,dc=au" side by side, on the one server.  I can do it 
> with separate servers, but there is the need to inform client programs 
> just which server to use (DNS LDAP discovery and 2.3/HEAD?).  I can also 
> run several SLAPD instances on the one server, but again there is the 
> problem of informing the client (which could be Joe Q. Public).
>
> So, it is possible to run non-overlapping suffixes on one server?
Of course. A single slapd server can manage multiple databases, and each 
database can have a suffix completely independent of the others. But 
that's only a very crude beginning of a solution. For corporate mergers, 
you eventually will want to be able to present a unified view of the two 
separate hierarchies. E.g., you may want everything under 
dc=BigCorp,dc=com to appear to be a subtree of dc=Cobber,dc=com,dc=au, 
something like ou=BigCorp,dc=Cobber,dc=com,dc=au. OpenLDAP easily 
supports this as well, through a variety of mechanisms. The simplest in 
OpenLDAP 2.2 would be to use back-ldap with some rewrite rules to point 
a subtree at the other. In OpenLDAP 2.3 there are even more efficient 
ways to do it:

database bdb
suffix dc=BigCorp,dc=com
...

database relay
suffix ou=BigCorp,dc=Cobber,dc=com,dc=au
relay dc=BigCorp,dc=com massage

database bdb
suffix dc=Cobber,dc=com,dc=au
overlay glue
glue-sub ou=BigCorp,dc=Cobber,dc=com,dc=au
...

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