DB2 pureScale has one of the best features known as WLB, ACR and CA and a brief introduction is here.

  • WLB (Work Load Balancing) – at the unit of work level is the capability unmatched in the industry and built at the driver level where it can distribute the work to different DB2 members without any application code change.
  • ACR (Automatic Client Reroute) – It is not only for DB2 pureScale but can be used with Standalone DB2, HADR, Q-Replication etc. This is one of the best piece of technology built at the driver level. DB2 also provides server level ACR by using UPDATE ALTERNATE SERVER but I am not that much fan of the server level ACR since the client has to connect at least once to cache that information and that is why my personal preference is to use it through driver. Once it is at the clinet, it becomes part of the release process of the software and guaranteed to work.
  • CA (Client Affinity) – Let a client have affinity towards a particulatr member with ACR capability.

Know that WLB and CA are mutually exclusive but WLB and ACR can coexist and same way ACR and CA can coexists but not WLB and CA.

Please refer to this excellent article on WLB, ACR and CA written by experts. This white paper can be downloaded from here.