[HBASE-7715] FSUtils#waitOnSafeMode can incorrectly loop on standby NN

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.94.4
• Fix Version/s: 0.94.5, 0.95.0
• Assignee: Ted Yu
• Reporter: Andrew Wang
• Created: 30/Jan/13 00:29
• Updated: 26/Feb/13 08:27
• Resolved: 31/Jan/13 07:53

Description

We encountered an issue where HMaster failed to start with an active NN not in safe mode and a standby NN in safemode. The relevant lines in FSUtils.java show the issue:

    while (dfs.setSafeMode(org.apache.hadoop.hdfs.protocol.FSConstants.SafeModeAction.SAFEMODE_GET)) {

This call skips the normal client failover from the standby to active NN, so it will loop polling the standby NN if it unfortunately talks to the standby first.

Issue Links

• is related to: HDFS-3507 DFS#isInSafeMode needs to execute only on Active NameNode