20-05-04 04:25:52 DEBUG ClientCnxn:818 - Reading reply sessionid:0x171dc5f77f00040, packet:: clientPath:null serverPath:null finished:false header:: 23,3 replyHeader:: 23,1099,0 request:: '/hbase-unsecure,F response:: s{116,116,1477381693974,1477381693974,0,24,0,0,0,18,966} 2020-05-04 04:25:52 DEBUG ClientCnxn:717 - Got ping response for sessionid: 0x171dc5f77f00040 after 4ms 2020-05-04 04:25:52 DEBUG ClientCnxn:818 - Reading reply sessionid:0x171dc5f77f00040, packet:: clientPath:null serverPath:null finished:false header:: 24,4 replyHeader:: 24,1099,0 request:: '/hbase-unsecure/master,F response:: #ffffffff000146d61737465723a3136303030ffffffe330ffffff86ffffffafffffffd2352bffffffc850425546a23a1773616e64626f782e686f72746f6e776f726b732e636f6d10ffffff807d18ffffff95ffffffcaffffffbdffffffe3ffffff9d2e10018ffffff8a7d,s{938,938,1588541230259,1588541230259,0,0,0,104106568998453260,71,0,938} 2020-05-04 04:25:52 DEBUG RpcClientImpl:351 - Use SIMPLE authentication for service MasterService, sasl=false 2020-05-04 04:25:52 DEBUG RpcClientImpl:716 - Connecting to sandbox.hortonworks.com/127.0.0.1:16000 2020-05-04 04:25:54 INFO RpcRetryingCaller:132 - Call exception, tries=10, retries=35, started=64734 ms ago, cancelled=false, msg= ... View more

Please read http://hbase.apache.org/book.html#architecture.master and http://hbase.apache.org/book.html#architecture.master. It sounds like your interpretation on what the HBase master does is very wrong. The HBase master is *not* involved with data access requests (scans in the shell). The verb "fail" means that when the process either stops or crashes for some reason. Sometimes processes can pause, yet recover. Part of this relates to the timeout in holding the ZooKeeper lock for distributed mutual exclusion between multiple Master processes. By default, that timeout is 30-60seconds at worst. ... View more