1.How to define metadata in hbase(meta&root)? HTable descriptor contains the details about an hbase table such as descriptor of all families is the table catalog table.-ROOT-or hbase.-meta if the table is read only maxsize of memstore when region split should occur. 2.how to configure WAL? WAL file is rolled when its size is about 95% of hdfs block size.you can configure the multiple r using parameter “h.base.regionserver.logroll.multipler”.&size using parameter “h.base.regionserver.hlog.blocksize”. 3.How to define size of memstore? Internal used by hbase shell interface to acess this metadata attribute which represents the maxsize of mematore after which its contents are fluahed into disk. Referred from google….