Hello,
Please be aware the MSA2312 FC array went End of Support Life on January 31, 2018. Because the system is EOSL there is very limited (or none) spare parts, service options, or support. If you have data on this system please be sure you have a backup.
The Storagae Management Utility (SMU) is the GUI web interface for managing the system. If you log into the system via an IP address in a web browser you are then using SMU. You can find more details in the following guide: https://support.hpe.com/hpesc/public/docDisplay?docId=emr_na-c01659237
Because this array is so old, your performance issue is likely due to new components on your SAN (OS, server, HBA/NIC, switch) that are no longer compatable with the MSA2312. Depending on recent upgrades and patches it may have caused a performance issue.
You should make sure all the drives are healthy, the RAID groups are fault tolerant, and pathing is correct.
Cheers,
Shawn
I work for Hewlett Packard Enterprise. The comments in this post are my own and do not represent an official reply from HPE. No warranty or guarantees of any kind are expressed in my reply.