[GitHub] [hbase] virajjasani commented on a change in pull request #1894: HBASE-21405 [DOC] Add Details about Output of "status 'replication'"

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virajjasani commented on a change in pull request #1894:
URL: https://github.com/apache/hbase/pull/1894#discussion_r440239542



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File path: src/main/asciidoc/_chapters/ops_mgt.adoc
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@@ -2629,6 +2629,91 @@ You can use the HBase Shell command `status 'replication'` to monitor the replic
 * `status 'replication', 'source'` -- prints the status for each replication source, sorted by hostname.
 * `status 'replication', 'sink'` -- prints the status for each replication sink, sorted by hostname.
 
+==== Understanding the output
+
+The command output will vary according to the state of replication. For example right after a restart
+and if destination peer is not reachable, no replication source threads would be running,
+so no metrics would get displayed:
+
+----
+hbase01.home:
+SOURCE: PeerID=1
+Normal Queue: 1
+No Reader/Shipper threads runnning yet.
+SINK: TimeStampStarted=1591985197350, Waiting for OPs...
+----
+
+Under normal circumstances, a healthy, active-active replication deployment would
+show the following:
+
+----
+    hbase01.home:
+      SOURCE: PeerID=1
+         Normal Queue: 1
+           AgeOfLastShippedOp=0, TimeStampOfLastShippedOp=Fri Jun 12 18:49:23 BST 2020, SizeOfLogQueue=1, EditsReadFromLogQueue=1, OpsShippedToTarget=1, TimeStampOfNextToReplicate=Fri Jun 12 18:49:23 BST 2020, Replication Lag=0
+      SINK: TimeStampStarted=1591983663458, AgeOfLastAppliedOp=0, TimeStampsOfLastAppliedOp=Fri Jun 12 18:57:18 BST 2020

Review comment:
       Just a question: For active-active replication, in order to get peerId of both clusters (defined in each other), we need to run `status 'replication'` at both clusters side right?
   Getting ageOfLastShipped etc metric values from remote cluster is also not that easy even if we want to display here.




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