Configuring a balanced storage system
The attachment of an external storage system to the system requires that specific settings are applied to set the characteristics of a balanced system.
About this task
- Setting the characteristics of the system to storage connections.
- Mapping logical units to these storage connections that allow the system to access the logical units.
You can use the virtualization features of the system to choose how your storage is divided and presented to hosts. While virtualization provides you with a great deal of flexibility, it also offers the potential to set up an overloaded storage system. A storage system is overloaded if the quantity of I/O transactions that are issued by the host systems exceeds the capability of the storage to process those transactions. If a storage system is overloaded, it causes delays in the host systems and might cause I/O transactions to time out in the host. If I/O transactions time out, the host logs errors and I/Os fail to the applications.
Scenario: You have an overloaded storage system.
Under this scenario, you used the system to virtualize a single array and to divide the storage across 64 host systems. If all host systems attempt to access the storage at the same time, the single array is overloaded.
To configure a balanced storage system that is not overloaded, follow these steps:
Procedure
What to do next
- Add more backend storage to the system to increase the quantity of I/O that can be processed by the storage system. The system provides virtualization and data migration facilities to redistribute the I/O workload of volumes across a greater number of MDisks without having to take the storage offline.
- Stop unnecessary FlashCopy mappings to reduce the number of I/O operations that are submitted to the backend storage. If you process FlashCopy operations in parallel, consider reducing the amount of FlashCopy mappings that start in parallel.
- Adjust the queue depth to limit the I/O workload that is generated by a host. Depending on the type of host and type of host bus adapters (HBAs), it might be possible to limit the queue depth per volume, limit the queue depth per HBA, or both. The system also provides I/O governing features that can limit the I/O workload that is generated by hosts.