There are 2 cars:
id-test-n03 : hasoop-hbase-master, hasoop-hbase-regionserver, hasoop-hbase-trift, hasoop-zookeeper-serverid-test-i03 : hasoop-hbase-regionserver
Both are Ubuntu Maverick machines, all the Hadoop (CDH3u3) and HBase packages are installed using the Cloudera CDH3 repository.
When using only id-test-n03 there were no problems. The HBase Wizard web console had 1 region server ( http: // id-test-n03: 60010 / master-status ), as expected.
After adding the area server to id-test-i03 , I found duplicated area servers (both have the same id-test-i03:60030 ) in the main HBase web console: 
Status in hbase shell was:
hbase(main):001:0> status 'detailed' version 0.90.4-cdh3u3 0 regionsInTransition 3 live servers id-test-i03:60020 1332390489086 requests=0, regions=0, usedHeap=24, maxHeap=983 id-test-n03.daum.net:60020 1332389557235 requests=0, regions=2, usedHeap=26, maxHeap=983 .META.,,1 stores=1, storefiles=0, storefileSizeMB=0, memstoreSizeMB=0, storefileIndexSizeMB=0 -ROOT-,,0 stores=1, storefiles=2, storefileSizeMB=0, memstoreSizeMB=0, storefileIndexSizeMB=0 id-test-i03:60020 1332390489086 requests=0, regions=0, usedHeap=0, maxHeap=0 0 dead servers
So, I tried to stop the region server on id-test-i03 , but found that only one region server was dead and the other was still alive: 
hbase(main):002:0> status 'detailed' version 0.90.4-cdh3u3 0 regionsInTransition 2 live servers id-test-n03.daum.net:60020 1332389557235 requests=0, regions=2, usedHeap=29, maxHeap=983 .META.,,1 stores=1, storefiles=0, storefileSizeMB=0, memstoreSizeMB=0, storefileIndexSizeMB=0 -ROOT-,,0 stores=1, storefiles=2, storefileSizeMB=0, memstoreSizeMB=0, storefileIndexSizeMB=0 id-test-i03:60020 1332390489086 requests=0, regions=0, usedHeap=0, maxHeap=0 1 dead servers id-test-i03.daum.net,60020,1332390489086
According to the information on the main web console, the difference between the duplicated regional servers is Start Code and Load . One has a host name, and the other has a fully qualified domain name in the startup code. One with the host name has an empty boot.
/etc/hosts/ for id-test-n03 and id-test-i03 :
127.0.0.1 localhost 192.168.1.1 id-test-n03 id-test-n03.daum.net 192.168.1.2 id-test-i03 id-test-i03.daum.net
hbase-site.xml for both machines:
<configuration> <property> <name>hbase.cluster.distributed</name> <value>true</value> </property> <property> <name>hbase.rootdir</name> <value>hdfs://id-test-n03:8020/hbase</value> </property> <property> <name>hbase.zookeeper.quorum</name> <value>id-test-n03</value> </property> </configuration>
Thanks for any advice.
The problem is solved by the following steps.
First deleted FQDNs in /etc/hosts for both machines:
127.0.0.1 localhost 192.168.1.1 id-test-n03 192.168.1.2 id-test-i03
Then commented out search $DOMAIN_NAME in /etc/resolv.conf for both machines:
#search daum.net nameserver 10.20.30.40
Finally, restart all Hadoop and HBase services on both machines.
Thus, Hadoop and HBase servers no longer use the fully qualified domain name, but only communicate with host names.
The addition and removal of region servers is reflected in the HBase ground state web console and hbase shell as expected.