Many of the metrics exposed in CDH 4/0.94 were removed with the refactorization of metrics in CDH 5/0.96. This patch restores the availability of the lists of live and dead RegionServers. In 0.94 this was a large nested structure as shown below, which included the RegionServer lists and metrics from each region.

{
    "name" : "hadoop:service=Master,name=Master",
    "modelerType" : "org.apache.hadoop.hbase.master.MXBeanImpl",
    "ZookeeperQuorum" : "localhost:2181",
....
    "RegionsInTransition" : [ ],
      "RegionServers" : [ {
        "key" : "localhost,48346,1390857257246",
        "value" : {
          "load" : 2,
.... 

CDH 5 Beta 1 and Beta 2 did not contain this list; they only displayed counts of the number of live and dead RegionServers. As of CDH 5.0.0, this list is now presented in a semi-colon separated field as follows:

{
    "name" : "Hadoop:service=HBase,name=Master,sub=Server",
    "modelerType" : "Master,sub=Server",
    "tag.Context" : "master",
    "tag.liveRegionServers" : "localhost,56196,1391992019130",
    "tag.deadRegionServers" :
    "localhost,40010,1391035309673;localhost,41408,1391990380724;localhost,38682,1390950017735",
    ...
}