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Posted to issues@ozone.apache.org by "Gargi Jaiswal (Jira)" <ji...@apache.org> on 2026/01/23 11:13:00 UTC
[jira] [Assigned] (HDDS-14389) [Website v2] [Docs] [Administrator Guide] OM HA, SCM HA failover behavior
[ https://issues.apache.org/jira/browse/HDDS-14389?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Gargi Jaiswal reassigned HDDS-14389:
------------------------------------
Assignee: Gargi Jaiswal
> [Website v2] [Docs] [Administrator Guide] OM HA, SCM HA failover behavior
> -------------------------------------------------------------------------
>
> Key: HDDS-14389
> URL: https://issues.apache.org/jira/browse/HDDS-14389
> Project: Apache Ozone
> Issue Type: Sub-task
> Components: documentation
> Reporter: Wei-Chiu Chuang
> Assignee: Gargi Jaiswal
> Priority: Major
>
> Our OM HA and SCM HA doc covers how multiple OM reaches consensus using Ratis.
> However, it misses another important part of story: client failover behavior.
> HadoopRpcOMFailoverProxyProvider: if client to OM is Hadoop RPC transport. The failover or retry may happen if (1) the OM is not not reachable, (2) not a leader, or (3) is a leader but not ready to accept requests.
> The failover will retry up to 500 times (ozone.client.failover.max.attempts), and 2 seconds between each failover retry (ozone.client.wait.between.retries.millis). If the OM is not aware of the current leader, client will try the next OM in round-robin fashion; otherwise, client will retry contacting the current leader.
> Additionally, it is crucial to ensure clients and OM have consistent node mapping configurations, otherwise failover may not reach the leader OM.
> GrpcOMFailoverProxyProvider: If client to OM is gRPC transport, the behavior is largely the same. But I don't have much experience with it so I'll just leave it as.
> Similarly, client (client, OM or Datanode) to SCM failover is controlled by a series of configuration properties in SCMClientConfig: hdds.scmclient.rpc.timeout, hdds.scmclient.max.retry.timeout, hdds.scmclient.failover.max.retry, hdds.scmclient.failover.retry.interval.
> Having these behaviors documented will help users troubleshoot problems.
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