Weighted prioritization of backend servers

The proxy server prioritizes back-end servers into 5 possible tiers. At a given time the proxy server will only use servers in one tier. When all the write servers within a tier fail. the proxy server will failover to the second tier. When the second tier fails it will failover to the third tier, so on and so forth.

Weighted prioritization is configurable for each back-end server within a split. This is done by setting a value for the attribute ibm-slapdProxyTier. The default value for this attribute is 1 and if the attribute is not present, the proxy treats the back-end server as a tier one server. Valid values for this attribute range from 1 to 5.

During startup, all servers in all tiers will be contacted. If the administrator wants the proxy server to start even if some of the back-end servers in different tiers are not available, then server groups can be used. For more information about server groups, see Server groups.