MSA 2050: Read Cache, how to check if it works?

I installed a 960GB SSD disk, to the pool I added a disk group, type "read cache". no problem. but also no apparent benefit.
I did some short tests but I didn't see any improvements, probably because the cache on the controllers is already sufficient.
is there any way to have (GUI, SNMP, CLI, ...) information about the operation of this disk? a hit cache, or something?