Couchbase suddenly stop working after certain time

Hi all,
I am facing a situation with my couchBase Server installed. I have installed it in my server but i have observed that after certain time the administration console(8091) become inaccessible. When i checked active process on this port(using netstat), no process is listening on port 8091. Itried to start couchBase manually with the command ./couchbase-server available on /opt/couchbase/bin directory. Now the administration console become accessible but after a certain time it become inacessible again. And no process is listening on 8091.

Please what can be the solution of this problem

Do any of the log files under /opt/couchbase/var/lib/couchbase/logs directory has any information of whether it crashed?