Extended processing capacity
As you move more data processing onto Db2, your processing needs can exceed the capacity of a single system. Using data sharing can help meet your ever-increasing capacity needs.
Without Db2 data sharing
- Copy the data, or split the data between separate Db2 subsystems.
This approach requires that you maintain separate copies of the data. There is no communication between or among Db2 subsystems, and no shared Db2 catalog or directory.
- Install another Db2 subsystem
and rewrite applications to access the data as distributed data.
This approach might relieve the workload on the original Db2 subsystem, but it requires changes to your applications and has performance overhead of its own. Nevertheless, if Db2 subsystems are separated by great distance or Db2 needs to share data with another system, the distributed data facility is still your only option.
- Install a larger processor and move the data and applications
to that machine.
This option can be expensive. In addition, this approach demands that your system come down while you move to the new machine.
With Db2 data sharing
With Db2 data sharing, you get the following benefits:
Support for incremental growth: A Parallel Sysplex® can grow incrementally, allowing you to add processing power in granular units and in a non-disruptive manner. The coupling technology of Parallel Sysplex along with the additional CPU power results in more throughput for users' applications. You no longer need to manage multiple copies of data, and all members of the data sharing group share a single Db2 catalog and directory.
Workload balancing: Db2 data sharing provides workload balancing so that when the workload increases or you add a new member to the group, you do not need to distribute your data or rewrite your applications. Db2 data sharing is unlike the partitioned-data approach to parallelism (sometimes called shared-nothing architecture), in which a one-to-one relationship exists between a database management system (DBMS) and a segment of data. When you add a new Db2 subsystem onto another central processor complex (CPC) in a data sharing environment, applications can access the same data through the new member just as easily as through any of the existing members.
Db2 works closely with the Workload Manager (WLM) component of z/OS® to ensure that incoming requests are optimally balanced across the members of a data sharing group. All members of the data sharing group have the same concurrent and direct read-write access to the data.
Capacity when you need it: A data sharing configuration can handle peak workloads well, such as end-of-quarter processing. You can have data sharing members in reserve, bring them online to handle peak loads, and then stop them when the peak passes.