I have three SQL database instances on a cloud server: A, B and C and the Server Installed Physical memory (RAM) is 32GB. The size of A (data+log file) is 44GB and B (data+log file) is 41GB. We ignore C since it has no databases in it and max memory set to 500MB.
Both instances A & B has it's memory set to the default size: 2147483647 MB. Although we have had no issues this is definitely not practical.
After some research, based on database activity, i decided that instance A memory allocation should be set to 20GB and B set to 10GB. In total 30/32 of the max physical memory in the system. Below shows the actual memory consumption. I am afraid if i set the max memory it will slow down response time. Is this configuration optimal in setting the SQL Max Server Memory for such databases and how can i simulate before applying?