Aihua Xu created HDFS-16200:
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Summary: Improve NameNode failover
Key: HDFS-16200
URL: https://issues.apache.org/jira/browse/HDFS-16200
Project: Hadoop HDFS
Issue Type: Task
Components: namanode
Affects Versions: 2.8.2
Reporter: Aihua Xu
Assignee: Aihua Xu
In a busy cluster, we are noticing the NameNode failover takes longer time
(over 10 minutes) and it causes cluster down time during the time period.
One bottleneck locates in resolving the client host's topology when the cluster
is not colocated with the computing hosts. NameNode resolves the client host's
topology and uses it to sort the hosts where the blocks locate in. Such
topology will be cached so the next access will be efficient, while if the
standby NameNode is newly restarted, then all the client hosts, e.g., YARN
hosts need to be resolved.
Solutions can be: 1) we can expose an API in DFSAdmin to load topology cache,
or 2) we can add a new configuration in HDFS cluster to skip resolving topology
for non-colocated HDFS cluster. Since client hosts and HDFS hosts are not
colocated, it's unnecessary to sort the DataNodes for the clients.
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