Re: load balancing openldap and handling referrals

[Daniel Tiefnig <openldap@qmail.infonova.at>]

Jan-Michael Ong wrote:

>       LDAP clients
>  _________|____________
> |____Load Balancer_____|
>   |       |       |
> master  slave1  slave2

> If an ldap update is sent to either slave1 or slave2, a referral is
> sent back to the client with the internal address of the master but
> since the internal address is not visible to the LDAP client (it only
> sees myldap.mydomain.net), how can it forward the request to the
> master?

it can't. unless you give your master a secondary (routeable) address. 
generally it's not a good idea to send update requests via the load 
balancer. (will just cause some useless traffic)

> Is this a setting that must be handled by the load-balancer or is
> there a smarter way of handling the referral?

i don't think your load balancer will understand LDAP..?

> If anyone of you are load balancing your ldap servers how do you
> handle LDAP commands that must modify the data (delete/modify/add)
> when it hits the slave and a referral is generated?

we have (had) a similar setup set up here, and we're sending update 
requests directly to the master and not via our loadbalancing l4switch. 
update scripts are running on the master host itself, (and _only_ 
there) connecting to localhost.
beside that, for some time now our master server isn't even in the 
load-balanced cluster anymore, "he"'s only handing updates to the 
slaves now.


hth,
daniel
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