740 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
Storwize V7000 performance overview
Storage virtualization with the IBM Spectrum Virtualize provides many administrative benefits. 
In addition, it can provide an increase in performance for some workloads. The caching 
capability of the IBM Spectrum Virtualize and its ability to stripe volumes across multiple disk 
arrays can provide a performance improvement over what can otherwise be achieved when 
midrange disk subsystems are used. 
To ensure that the performance levels of your system are maintained, monitor performance 
periodically to provide visibility to potential problems that exist or are developing so that they 
can be addressed in a timely manner. 
Performance considerations
When you are designing the IBM Spectrum Virtualize infrastructure or maintaining an existing 
infrastructure, you must consider many factors in terms of their potential effect on 
performance. These factors include, but are not limited to, dissimilar workloads that are 
competing for the same resources, overloaded resources, insufficient available resources, 
poor performing resources, and similar performance constraints. 
Remember the following high-level rules when you are designing your storage area network 
(SAN) and IBM Spectrum Virtualize layout:
/SM590000Host-to-System inter-switch link (ISL) oversubscription
This area is the most significant input/output (I/O) load across ISLs. The recommendation 
is to maintain a maximum of 7-to-1 oversubscription. A higher ratio is possible, but it tends 
to lead to I/O bottlenecks. This suggestion also assumes a core-edge design, where the 
hosts are on the edges and the Storwize V7000 is the core. 
/SM590000Storage-to-System ISL oversubscription
This area is the second most significant I/O load across ISLs. The maximum 
oversubscription is 7-to-1. A higher ratio is not supported. Again, this suggestion assumes 
a multiple-switch SAN fabric design.
/SM590000Node-to-node ISL oversubscription
This area does not apply to Storwize V7000 clusters composed of a unique control 
enclosure. This area is the least significant load of the three possible oversubscription 
bottlenecks. In standard setups, this load can be ignored. Although this area is not entirely 
negligible, it does not contribute significantly to the ISL load. However, node-to-node ISL 
oversubscription is mentioned here in relation to the split-cluster capability that was made 
available since V6.3 (HyperSwap).
When the system is running in this manner, the number of ISL links becomes more 
important. As with the storage-to-System ISL oversubscription, this load also requires a 
maximum of 7-to-1 oversubscription. Exercise caution and careful planning when you 
determine the number of ISLs to implement. If you need assistance, contact your IBM 
representative.
/SM590000ISL trunking/port channeling
For the best performance and availability, use ISL trunking or port channeling. 
Independent ISL links can easily become overloaded and turn into performance 
bottlenecks. Bonded or trunked ISLs automatically share load and provide better 
redundancy in a failure.