IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

174 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

The advantages of SAN Volume Controller remote copy is that we can implement such

relationships between two SAN Volume Controller clusters with different backend disk

subsystems. in this case, you reduce the overall cost of the disaster recovery infrastructure

implemented on the production site (first site) high performance backend disk subsystems

and on the recovery site low-cost backend disk subsystems, even if backend disk subsystems

copy services functions are not compatible (for example, different models, different

constructors...). Figure 6-4 represents an example of a remote copy relationship between two

SAN Volume Controller clusters. This relationship is established at the vDisk level and doesn’t

depend of the backend disk storage subsystem.

Figure 6-4 Synchronous remote copy relationship between 2 SAN Volume Controller clusters

6.1.4 SAN Volume Controller performance considerations

The SAN Volume Controller cluster is scalable up to eight I/O groups (eight pairs of SAN

Volume Controller nodes), and the performance is almost linear when adding more I/O groups

to a SAN Volume Controller cluster, until it becomes limited by other components in the

storage infrastructure. While virtualization with the SAN Volume Controller provides a great

deal of flexibility, it does not diminish the necessary to have a SAN and disk subsystems

which can deliver the desired performance.

In the following section, we present the IBM SAN Volume Controller concepts and discuss the

performance of the SAN Volume Controller. In this section, we assume there are no

bottlenecks in the SAN or on the disk subsystem.

Determine the number of I/O groups

The SAN Volume Controller cluster consists of I/O groups, where each I/O group consists of a

pair of SAN Volume Controller nodes (also called storage engine). Since the SAN Volume

Controller cluster is linearly scalable, we will first focus on performance for a single I/O group.