[HDFS-3618] SSH fencing option may incorrectly succeed if nc (netcat) command not present

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.0.0-alpha
• Component/s: auto-failover
• Labels: BB2015-05-TBR
• Assignee: Vinayakumar B
• Reporter: Brahma Reddy Battula
• Created: 09/Jul/12 09:32
• Updated: 10/Jan/17 23:04

Description

Started NN's and zkfc's in Suse11.
Suse11 will have netcat installation and netcat -z will work(but nc -z wn't work)..
While executing following command, got command not found hence rc will be other than zero and assuming that server was down..Here we are ending up without checking whether service is down or not..

LOG.info(
            "Indeterminate response from trying to kill service. " +
            "Verifying whether it is running using nc...");
        rc = execCommand(session, "nc -z " + serviceAddr.getHostName() +
            " " + serviceAddr.getPort());
        if (rc == 0) {
          // the service is still listening - we are unable to fence
          LOG.warn("Unable to fence - it is running but we cannot kill it");
          return false;
        } else {
          LOG.info("Verified that the service is down.");
          return true;          
        }

Issue Links

• is duplicated by: HDFS-11308 NameNode doFence state judgment problem