Arpit Agarwal created HDFS-5448:
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Summary: Synchronize NN registrations across block pools
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
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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