[jira] [Updated] (AMBARI-17660) EU Downgrade Does Not Stop Services

["Jonathan Hurley (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AMBARI-17660?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Hurley updated AMBARI-17660:
-------------------------------------
    Attachment: AMBARI-17660.patch

> EU Downgrade Does Not Stop Services
> -----------------------------------
>
>                 Key: AMBARI-17660
>                 URL: https://issues.apache.org/jira/browse/AMBARI-17660
>             Project: Ambari
>          Issue Type: Bug
>          Components: ambari-server
>    Affects Versions: 2.2.0
>            Reporter: Jonathan Hurley
>            Assignee: Jonathan Hurley
>            Priority: Blocker
>             Fix For: 2.4.0
>
>         Attachments: AMBARI-17660.patch
>
>
> When downgrading an express upgrade, the orchestration of the downgrade does not perform the same steps as the upgrade did. Namely, the stopping of high- and low-level services is not present. This leads to a scenario like this:
> - Upgrade HDP 2.x to 2.y
> -- Stop Storm
> -- Stop ZK
> -- Update Stack to 2.y
> -- Restart ZK on 2.y
> -- Restart Storm on 2.y
> - Downgrade  HDP 2.y to 2.x
> -- Update Stack to 2.x
> -- Restart ZK on 2.x
> -- Restart Storm on 2.x
> Notice that we didn't stop the running services. This leads to a problem where actions which must take place while services are down can't complete successfully.
> The case in point is Storm. Between HDP 2.4 and HDP 2.5, Storm changed the name of a serialized class. Part of the Storm upgrade/downgrade is to always delete local storm data. However, during an EU, if Nimbus and Supervisor are co-located on the same host, Supervisor will write out 2.5 data since it wasn't shut down. Consider:
> - Nimbus deletes local data and restarts on the downgrade version
> - A running 2.5 Supervisor on the same host then re-creates that directory and puts 2.5 data back in
> - When the 2.5 Supervisor goes to downgrade and restart, it can't delete that data again since Nimbus is already running and would stop.
> For this reason, we should always ensure that services are stopped on the downgrade for an EU. 



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