If you are seeing decreased performance within your storage infrastructure, there are a few things you can look at on your storage system to rule out the possibility of the issue being with your system array itself or to find out the underlying cause of the issue itself. Today, we will look at one of the first things you can examine in determining the reasoning behind poor performance – SP utilization.
What is a SP?
SP is the storage processor on the array. The SP is a device that each client host is connected to via iSCSI or Fibre Channel that leverages requests going to the storage subsystems. With determining whether SP Utilization is the underlying cause of performance issues, you should see if the utilization on the storage processor is too high. Going over 50% on the SP utilization may be an indication of a performance issue.
Each system or storage array is equipped with two storage processors. These SPs are meant to work in a redundant fashion in the sense that if one of the SPs fail, the other SP should have enough capacity on it to be able to take over the additional load from the failed SP without having a significant performance impact on your system overall.
What Happens With Two SPs with High Utilization
So, if your storage array has one of the storage processors running at 75% utilization and the other running at 50% utilization, this may be the cause of your poor performance. While this utilization may not be the cause of poor performance, it definitely puts you into a risky situation. If one of those SPs were to fail, reboot, or go down for any reason, then you will definitely see significant performance problems on all of your client hosts that are attached to that storage array,
Applications that Cause High SP Utilization
The types of applications that can lead to performance issues will depend on what type of application it is and what the application is doing. Is it a transactional database where the writes coming in are of a transactional nature or are the writes more sequential? If the application is transactional, it will be constantly exchanging data to your LUNs – reading data, writing data, and changing data – like a database such as an OLTP system. If it is sequential, like an arching tape system, the application will only be appending data onto an existing drive.
The more transactional workloads tend to be more stressful on your storage processor. So, if you needed to bring down your SP utilization by moving a environment type off of your system, the transactional tape system would be your best choice to lower SP utilization within your system.