[jira] [Commented] (AMBARI-16028) Namenode marked as INITIAL standby could potentially never start if other namenode is down

["Jayush Luniya (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AMBARI-16028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15252864#comment-15252864 ] 

Jayush Luniya commented on AMBARI-16028:
----------------------------------------

*Fix:*
# The fix is to maintain a bootstrap marker file (similar to the way we keep a name node formatted marker file)
# In the INITIAL_START phase (during cluster deployment) we will always force bootstrap so as to enforce the name node marked as Standby to wait for the Active name node to come up, bootstrap and start in STANDBY node.
# Once we are out of INITIAL_START phase, we will bootstrap only if this name node has not been bootstrapped in the past. 
# We will not enforce bootstrapping only in the INITIAL_START phase because there is a possibility during cluster deployment that both name nodes don’t start and hence bootstrapping out of INITIAL_START phase would be required in this case.

> Namenode marked as INITIAL standby could potentially never start if other namenode is down
> ------------------------------------------------------------------------------------------
>
>                 Key: AMBARI-16028
>                 URL: https://issues.apache.org/jira/browse/AMBARI-16028
>             Project: Ambari
>          Issue Type: Bug
>          Components: stacks
>    Affects Versions: 2.2.0
>            Reporter: Jayush Luniya
>            Priority: Critical
>             Fix For: 2.4.0
>
>
> *Issue:*
> # During Namenode HA blueprint deployment, we configure the name nodes to start in active/standby mode based on the following properties
> {code}
>      {
>         "hadoop-env": {
>           "properties" : {
>             "dfs_ha_initial_namenode_active" : "jay-msft-1.c.pramod-thangali.internal",
>             "dfs_ha_initial_namenode_standby" : "jay-msft-2.c.pramod-thangali.internal”
>           }
>         }
>       }
> {code}
> # The current logic is to always bootstrap the name node marked as standby. 
> # This will lead to the Namenode marked as Standby to never start under the following situation
> - Cluster is deployed successfully
> - Both name nodes are stopped
> - Start the name node marked as standby. Namenode will never start.
> - This is because the standby name node will try to bootstrap again. 
> - However to bootstrap a name node an active name node is required. Based on the HDFS logic the first step done when bootstrapping is to connect to the Active Namenode. 
> - Also there is no need to bootstrap here as the name node should already be bootstrapped and should come back up as “Active"



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