Hi, My answers inline...
On 1/7/09 12:05 PM, "Genady" <[email protected]> wrote: > Hi, > > > > Could somebody explain an expected HBase 0.18.1 nodes behavior in case > Hadoop cluster failover for a following reasons: > > > > - HBase master region server fails You need to manually set a different machine as master and redistribute the configuration files on all other region servers and restart the cluster. Maybe someone in the development team could explain if this will change with Zookeeper integration. > > > - HBase slave region server fails This is handled transparently. Regions served by the failed region server are reassigned to the rest of the region servers. > > - Hadoop master server fails I suppose you mean the HDFS namenode. Currently, the namenode is a single point of failure in HDFS and needs manual intervention to configure a new namenode. A secondary namenode can be configured, however this one only keeps a metadata replica and does not act as failover node. http://wiki.apache.org/hadoop/NameNode > > - Hadoop slave server fails If a HDFS datanode fails it's files are already replicated on 2 other datanodes. Eventually the replication will be fixed by the namenode - creating third replica on one of remaining datanodes. > > - Hadoop master and HBase master are fail ( in case they're > installed on the same computer and for instance disk has failover) These servers run independently so you can see above what happens. > > - HBase slave region server is failed but HBase data could be > recovered and copied to other node and the new node is added instead of > failed one. Hbase region servers don't actually hold the data. Data is stored in HDFS. Region servers just serve regions and when the region server fails the regions are reassigned (see above). Cosmin > > > > Any help would be appreciated, > > > > Gennady Gilin > > > >
