Technical data

96 Brocade ServerIron ADX Advanced Server Load Balancing Guide
53-1003441-01
Cache persistence using URL hashing
2
Parsing using the “pattern string” with a specified string length
ServerIronADX(config)#csw-policy p1
ServerIronADX(config-csw-p1)#match r1 forward 1
ServerIronADX(config-csw-p1)#match r1 hash-persist url search-host “www.” offset
0 length 5
Supporting multiple pattern search for the same rule
ServerIron ADX supports multiple pattern search for the same rule. Support is provided for up to 4
different pattern strings as shown in the following example.
Force rehash
By default, the following will happen when the cache server goes down and goes up again:
• When the cache server goes down, its hash bucket will be taken by other active cache server.
• When a failed cache server comes up, the hash bucket will be allocated if, and only if, there
are hash buckets without server association. In most cases, where traffic is evenly spread,
none of the hash buckets will be available to the new server.
When a cache server goes down and up, the group hash table is not rehashed and the other server
won't be affected. This will make the ServerIron ADX maintain the persistence of the cache servers.
Though in a situation where all of the hash table entries are taken by other cache servers, the
failed cache server may not be able to process traffic after it comes back to active. This also
applies to the situation that the new cache server is added to the group.
You can configure the entire hash table to be re-hashed when a new cache server is added or a
failed cache server recovers. Use the csw-force-rehash command within the cache group
configuration to enable automatic rehash of hash buckets.
ServerIronADX(config)#server cache-group 1
ServerIronADX(config-tc-1)#csw-force-rehash
Syntax: [no] csw-force-rehash
TABLE 8 Results for parsing the host string of a URL by method
Method String used for hashing
pattern string only brocade.com
pattern string with a
delimiter of “.”
brocade
pattern string with a
length value of 4”
broc
ServerIronADX(config)#csw-policy p1
ServerIronADX(config-csw-p1)#match r1 forward 10
ServerIronADX(config-csw-p1)#match r1 hash-persist url search-url “v1” offset 0
ServerIronADX(config-csw-p1)#match r1 hash-persist url search-url “v2” offset 0
ServerIronADX(config-csw-p1)#match r1 hash-persist url search-url “v3” offset 0
delimiter “&”
ServerIronADX(config-csw-p1)#match r1 hash-persist url search-url “v4” offset 0
length 3
ServerIronADX(config-csw-p1)#match r2 forward 20
ServerIronADX(config-csw-p1)#match r2 hash-persist url search-host “m1” offset 0
ServerIronADX(config-csw-p1)#match r2 hash-persist url search-host “m2” offset 0