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https://issues.apache.org/jira/browse/HDDS-1175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17260153#comment-17260153
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runzhiwang commented on HDDS-1175:
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[~bharat] Yes isLeaderReady helps following scenario. So I only need to
implement "Leader Lease".
bq. For example, server1 (leader): applyIndex = 2, commitIndex = 2, server2:
applyIndex = 1, commitIndex = 2. When server1 step down, server2 become leader,
and client read from server2,
bq. because server2's applyIndex less than commitIndex, client will read old
data.
> Serve read requests directly from RocksDB
> -----------------------------------------
>
> Key: HDDS-1175
> URL: https://issues.apache.org/jira/browse/HDDS-1175
> Project: Hadoop Distributed Data Store
> Issue Type: Sub-task
> Components: OM HA, Ozone Manager
> Reporter: Hanisha Koneru
> Assignee: Hanisha Koneru
> Priority: Major
> Labels: pull-request-available
> Attachments: HDDS-1175.001.patch
>
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> We can directly server read requests from the OM's RocksDB instead of going
> through the Ratis server. OM should first check its role and only if it is
> the leader can it server read requests.
> There can be a scenario where an OM can lose its Leader status but not know
> about the new election in the ring. This OM could server stale reads for the
> duration of the heartbeat timeout but this should be acceptable (similar to
> how Standby Namenode could possibly server stale reads till it figures out
> the new status).
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