[jira] [Updated] (HDFS-6800) Determine how Datanode layout changes should interact with rolling upgrade

["Liang Xie (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDFS-6800?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Liang Xie updated HDFS-6800:
----------------------------

    Summary: Determine how Datanode layout changes should interact with rolling upgrade  (was: Detemine how Datanode layout changes should interact with rolling upgrade)

> Determine how Datanode layout changes should interact with rolling upgrade
> --------------------------------------------------------------------------
>
>                 Key: HDFS-6800
>                 URL: https://issues.apache.org/jira/browse/HDFS-6800
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: datanode
>    Affects Versions: 2.6.0
>            Reporter: Colin Patrick McCabe
>
> We need to handle attempts to rolling-upgrade the DataNode to a new storage directory layout.
> One approach is to disallow such upgrades.  If we choose this approach, we should make sure that the system administrator gets a helpful error message and a clean failure when trying to use rolling upgrade to a version that doesn't support it.  Based on the compatibility guarantees described in HDFS-5535, this would mean that *any* future DataNode layout changes would require a major version upgrade.
> Another approach would be to support rolling upgrade from an old DN storage layout to a new layout.  This approach requires us to change our documentation to explain to users that they should supply the {{\-rollback}} command on the command-line when re-starting the DataNodes during rolling rollback.  Currently the documentation just says to restart the DataNode normally.
> Another issue here is that the DataNode's usage message describes rollback options that no longer exist.  The help text says that the DN supports {{\-rollingupgrade rollback}}, but this option was removed by HDFS-6005.



--
This message was sent by Atlassian JIRA
(v6.2#6252)