You are viewing a plain text version of this content. The canonical link for it is here.

Posted to hdfs-issues@hadoop.apache.org by "Harsh J (JIRA)" <ji...@apache.org> on 2014/12/09 23:53:13 UTC

[jira] [Created] (HDFS-7501) TransactionsSinceLastCheckpoint can be negative on SBNs

Harsh J created HDFS-7501:
-----------------------------

             Summary: TransactionsSinceLastCheckpoint can be negative on SBNs
                 Key: HDFS-7501
                 URL: https://issues.apache.org/jira/browse/HDFS-7501
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: namenode
    Affects Versions: 2.5.0
            Reporter: Harsh J
            Priority: Trivial


The metric TransactionsSinceLastCheckpoint is derived as FSEditLog.txid minus NNStorage.mostRecentCheckpointTxId.

In Standby mode, the former does not increment beyond the loaded or last-when-active value, but the latter does change due to checkpoints done regularly in this mode. Thereby, the SBN will eventually end up showing negative values for TransactionsSinceLastCheckpoint.

This is not an issue as the metric only makes sense to be monitored on the Active NameNode, but we should perhaps just show the value 0 by detecting if the NN is in SBN form, as allowing a negative number is confusing to view within a chart that tracks it.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)