Configuring the WSM using Device Manager

Hash

The hash metric uses IP address information in the client request to select a server. The specific IP address information used depends on the application, as described below.

For Application Redirection, the client destination IP address is used. All requests for a specific IP destination address will be sent to the same server. This is particularly useful for maximizing successful cache hits.
For SLB, the client source IP address is used. All requests from a specific client will be sent to the same server. This option is useful for applications where client information must be retained between sessions.

For FWLB, both the source and destination IP addresses are used to ensure that the two unidirectional flows of a given session are redirected to the same firewall. When selecting a server, a mathematical hash of the relevant IP address information is used as an index into the list of currently available servers. Any given IP address information will always have the same hash result, providing natural persistence, as long as the server list is stable. However, if a server is added to or leaves the mix, then a different server might be assigned to a subsequent session with the same IP address information even though the original server is still available. Open connections are not cleared.

Note: The hash metric provides more distributed load balancing than minimum misses at any given instant. It should be used if the statistical load balancing achieved using minimum misses is not as optimal as desired. If the load balancing statistics with minimum misses indicate that one server is processing significantly more requests over time than other servers, consider using the hash metric.