The customer did a fresh install of UIM and UMP on Rhel 6.5 servers, and without any load on the system the USM would continuously report the same error message, making the portlet unusable:
An unknown error has occurred. Refreshing your browser may resolve the issue.
com.firehunter.ump.exceptions.DataFactoryException : null
Method: getAlarms(Long: 1470407413000, Long: 0)
Method: getAlarms(Long: 1470407413000, Long: 0, Boolean: true)
Method: getAlarmsFromDb(Long: 1470407413000, Long: 0, Boolean: true)
Method: getAlarmFiltersForAcl(String: Superuser)
(80) Session error, Unable to open a client session for <hubip>:48000: Connection timed out
Caused by: java.net.ConnectException: Connection timed out
Newer versions of the USM portlet did not resolve the issue, and the USM tracing enabled on the portlet did not give any useful information about the problem.
This was caused by a known issue with Linux 3.10.0-229.el7.x86_64.
UIM and UMP 8.4 running on Rhel 6.5
To ultimately resolve the issue, the customer had to upgrade to kernel version Linux 3.10.0-327.36.3.el7.x86_64. Once this was done the connection timeout errors were resolved without any further intervention on the application side.