[jira] [Resolved] (HDFS-5448) Datanode should generate its ID on first registration

["Arpit Agarwal (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDFS-5448?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Arpit Agarwal resolved HDFS-5448.
---------------------------------

       Resolution: Fixed
    Fix Version/s: Heterogeneous Storage (HDFS-2832)

Thanks Nicholas. I committed this to branch HDFS-2832.

> Datanode should generate its ID on first registration
> -----------------------------------------------------
>
>                 Key: HDFS-5448
>                 URL: https://issues.apache.org/jira/browse/HDFS-5448
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: datanode
>    Affects Versions: Heterogeneous Storage (HDFS-2832)
>            Reporter: Arpit Agarwal
>            Assignee: Arpit Agarwal
>             Fix For: Heterogeneous Storage (HDFS-2832)
>
>         Attachments: h5448.01.patch, h5448.03.patch, h5448.04.patch
>
>
> Prior to the heterogeneous storage feature, each Datanode had a single storage ID which was generated by the Namenode on first registration. The storage ID used fixed Datanode identifiers like IP address and port, so that in a federated cluster, for example, all NameNodes would generate the same storage ID.
> With Heterogeneous storage, we have replaced the storage ID with a per-datanode identifier called the Datanode-UUID. The Datanode UUID is also assigned by a NameNode on first registration. In a federated cluster with multiple namenodes, there are two ways to ensure a unique Datanode UUID allocation:
> # Synchronize initial registration requests from the BPServiceActors. If a Datanode UUID is already assigned we don't need to synchronize.
> # The datanode assigns itself a UUID on initialization.



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