HTOP from the SSH console and reviewing the /var/log/messages might help find something
If you are running 9.5.1 MR1 you may be having memory issues, especially if you have an older appliance. We experienced major memory usage issues upon upgrading to 9.5.1.MR1 which can only be mitigated by stopping and starting the dbserver service when the EPS is at peak.
Run the htop command from a Putty session on the ESM and look at your memory utilization.
There is an MR2 release that some are saying addresses the issue, however, we have not applied this yet.