Hash persistence

Hash persistence allows you to create a persistence hash based on an existing iRule that uses the persist iRule command. Using hash persistence is the same as using universal persistence, except that with hash persistence, the resulting persistence key is a hash of the data, rather than the data itself.

rule my_persist_irule {
when HTTP_REQUEST { persist hash [HTTP::header myheader] }
}

Hash profile settings

Setting	Description	Default Value
Name	Specifies a unique name for the profile. This setting is required.	No default value
Persistence Type	Specifies the type of persistence profile. This setting is required.	Hash
Match Across Services	Specifies that all persistent connections from a client IP address that go to the same virtual IP address also go to the same node.	Disabled (Cleared)
Match Across Virtual Servers	Specifies that all persistent connections from the same client IP address go to the same node.	Disabled (Cleared)
Match Across Pools	Specifies that the BIG-IP system can use any pool that contains this persistence entry.	Disabled (Cleared)
Hash Algorithm	Specifies the algorithm the system uses for hash persistence load balancing. The hash result is the input for the algorithm. Possible settings are: Default: Specifies that the system uses the index of pool members to obtain the hash result for the input to the algorithm. CARP: Specifies that the system uses the Cache Array Routing Protocol (CARP) to obtain the hash result for the input to the algorithm.	Default
Hash Offset	Specifies the start offset within the packet from which the system begins the hash when performing hash persistence load balancing. The default value of 0 (zero) indicates no offset.	0
Hash Length	Specifies the length of data within the packet, in bytes, that the system uses to calculate the hash value when performing hash persistence load balancing.	0
Hash Start Pattern	Specifies the string expression (Tcl regex) that describes the starting location of the hash pattern that the system uses to perform hash persistence load balancing.	No default value
Hash End Pattern	Specifies the string expression (Tcl regex) that describes the ending location of the hash pattern that the system uses to perform hash persistence load balancing.	No default value
Hash Buffer Limit	Specifies the maximum amount of data within which the system searches to locate the hashing pattern.	0
Hash More	Specifies that the system performs another hash operation after the current hash operation completes.	Disabled (unchecked)
iRule	Specifies an iRule to run that determines the persistence entry.	None
Timeout	The setting specifies the duration, in seconds, of a persistence entry. For background information on setting timeout values, see Chapter 1, Introducing BIG-IP Local Traffic Manager. Possible values are: Specify: Specifies the number of seconds before the persistence entry expires. Indefinite: Specifies that the persistence entry does not expire.	180
Override Connection Limit	Specifies, when checked (enabled), that the system allows you to specify that pool member connection limits are overridden for persisted clients. Per-virtual connection limits remain hard limits and are not overridden.	Disabled (Cleared)