Thanks again for your prompt response, and insightful troubleshooting.
I changed hostname from localhost to vcs-node1 in files 'main.cf', '/etc/sysconfig/network' and '/etc/hosts', and rebooted the server.
[root@vcs-node1 ~]# cd /var/VRTSvcs/log/
[root@vcs-node1 log]# ls -lrt
total 36
drwxr-x---. 2 root root 4096 Nov 13 15:35 vxfen
-rw-r--r--. 1 root root 654 Nov 13 17:21 uuidconfig.log
-rw-r--r--. 1 root root 1480 Nov 14 16:47 CmdServer-log_A.log
drwxr-xr-x. 2 root root 4096 Nov 14 16:47 tmp
-rw-r--r--. 1 root root 9221 Nov 14 16:47 engine_A.log
-rw-r--r--. 1 root root 477 Nov 14 16:47 HostMonitor_A.log
-rw-r--r--. 1 root root 1592 Nov 14 17:03 hastart.log
[root@vcs-node1 log]# tail -n 51 engine_A.log
2012/11/14 14:48:12 VCS INFO V-16-1-10196 Cluster logger started
2012/11/14 16:47:02 VCS NOTICE V-16-1-11022 VCS engine (had) started
2012/11/14 16:47:02 VCS NOTICE V-16-1-11027 VCS engine startup arguments=-onenode
2012/11/14 16:47:02 VCS NOTICE V-16-1-11050 VCS engine version=6.0
2012/11/14 16:47:02 VCS NOTICE V-16-1-11051 VCS engine join version=6.0.10.0
2012/11/14 16:47:02 VCS NOTICE V-16-1-11052 VCS engine pstamp=6.0.100.000-GA-2012-07-20-16.30.01
2012/11/14 16:47:02 VCS NOTICE V-16-1-10115 Using GABSIM
2012/11/14 16:47:02 VCS NOTICE V-16-1-14032 Forming a one node cluster
2012/11/14 16:47:02 VCS INFO V-16-1-10196 Cluster logger started
2012/11/14 16:47:06 VCS NOTICE V-16-1-10619 'HAD' starting on: vcs-node1
2012/11/14 16:47:07 VCS INFO V-16-1-10125 GAB timeout set to 30000 ms
2012/11/14 16:47:07 VCS INFO V-16-1-10077 Received new cluster membership
2012/11/14 16:47:07 VCS NOTICE V-16-1-10112 System (vcs-node1) - Membership: 0x1, DDNA: 0x0
2012/11/14 16:47:07 VCS NOTICE V-16-1-10086 System vcs-node1 (Node '0') is in Regular Membership - Membership: 0x1
2012/11/14 16:47:07 VCS NOTICE V-16-1-10322 System vcs-node1 (Node '0') changed state from CURRENT_DISCOVER_WAIT to LOCAL_BUILD
2012/11/14 16:47:11 VCS WARNING V-16-1-10030 UseFence=NONE. Hence do not need fencing
2012/11/14 16:47:11 VCS NOTICE V-16-1-10322 System vcs-node1 (Node '0') changed state from LOCAL_BUILD to RUNNING
2012/11/14 16:47:11 VCS NOTICE V-16-1-10016 Agent /opt/VRTSvcs/bin/HostMonitor for resource type HostMonitor successfully started at Wed Nov 14 16:47:11 2012
2012/11/14 16:47:13 VCS INFO V-16-1-10151 Invoking trigger to dump environment variables
2012/11/14 16:47:14 VCS INFO V-16-6-15015 (vcs-node1) hatrigger:/opt/VRTSvcs/bin/triggers/sysup is not a trigger scripts directory or can not be executed
2012/11/14 16:47:15 VCS INFO V-16-6-15023 (vcs-node1) dump_tunables:
########## VCS Environment Variables ##########
VCS_CONF=/etc/VRTSvcs
VCS_DIAG=/var/VRTSvcs
VCS_HOME=/opt/VRTSvcs
VCS_LOG_AGENT_NAME=
VCS_LOG_CATEGORY=6
VCS_LOG_SCRIPT_NAME=hatrigger
VCS_LOG=/var/VRTSvcs
########## Other Environment Variables ##########
CONSOLETYPE=vt
LANG=en_US.UTF-8
LANGSH_SOURCED=1
LD_LIBRARY_PATH=/opt/VRTSvcs/lib:
PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/sbin:/usr/sbin:/bin:/usr/bin:/opt/VRTSvcs/bin
previous=N
PREVLEVEL=N
PWD=/var/VRTSvcs/diag/had
runlevel=5
RUNLEVEL=5
SHLVL=5
TERM=linux
UPSTART_EVENTS=runlevel
UPSTART_INSTANCE=
UPSTART_JOB=rc
_=/usr/bin/env
2012/11/14 16:47:15 VCS INFO V-16-6-15002 (vcs-node1) hatrigger:hatrigger executed /opt/VRTSvcs/bin/internal_triggers/dump_tunables vcs-node1 1 successfully
2012/11/14 16:47:17 VCS NOTICE V-16-1-10438 Group VCShmg has been probed on system vcs-node1
2012/11/14 16:47:17 VCS NOTICE V-16-1-10435 Group VCShmg will not start automatically on System vcs-node1 as the system is not a part of AutoStartList attribute of the group.
[root@vcs-node1 log]# tail -n2 CmdServer-log_A.log
2012/11/14 16:45:46 VCS WARNING V-16-1-10604 Unsuccessful open of service
2012/11/14 16:47:02 VCS INFO V-16-1-11237 CmdServer[security off] is Up
[root@vcs-node1 log]# cat HostMonitor_A.log
#
# Log Name: HostMonitor
# System: vcs-node1
# SysInfo: Linux:vcs-node1,#1 SMP Tue May 10 15:42:40 EDT 2011,2.6.32-131.0.15.el6.x86_64,x86_64
# Created: 2012/11/14 16:47:17
#
2012/11/14 16:47:17 VCS INFO V-16-10061-14001 HostMonitor:VCShm:monitor:Updating System attribute with CPU usage = 11% and Swap usage = 0%.
2012/11/14 16:47:47 VCS INFO V-16-10061-14001 HostMonitor:VCShm:monitor:Updating System attribute with CPU usage = 1% and Swap usage = 0%.
[root@vcs-node1 log]# cat tmp/HostMonitor-0
ALL
[root@vcs-node1 log]# tail -n4 hastart.log
boottime = <1352911587>, modifytime = <1352904492>
Wed Nov 14 17:03:04 GMT 2012
File was modified after system boot,
boottime = <1352911587>, modifytime = <1352911622>