http://docs.couchbase.com/couchbase-manual-2.5/cb-install/#couchbase-getting-started-hostnames

1、sudo /etc/init.d/couchbase-server stop

or Linux 2.0 this is /opt/couchbase/var/lib/couchbase/ip. This file contains the identified IP address of the node once it is part of a cluster. Open the file, and add a single line containing the hostname, as configured in the previous step.

For Linux 2.0.1. You update the ip_start file with the hostname. The file is at this location: /opt/couchbase/var/lib/couchbase/ip_start.

Delete the files under:

/opt/couchbase/var/lib/couchbase/data/* /opt/couchbase/var/lib/couchbase/mnesia/* /opt/couchbase/var/lib/couchbase/config/config.dat

Execute:

sudo /etc/init.d/couchbase-server start

======================= If can’t not, maybe reinstall. just delete /opt/couchbase/var/lib/couchbase/config/config.dat

then server stop, restart. then can resetup.