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Posted to issues@ozone.apache.org by "Sammi Chen (Jira)" <ji...@apache.org> on 2020/03/31 07:32:00 UTC
[jira] [Updated] (HDDS-3306) Support configurable data consistency
level
[ https://issues.apache.org/jira/browse/HDDS-3306?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sammi Chen updated HDDS-3306:
-----------------------------
Summary: Support configurable data consistency level (was: Support client side configurable data consistency level)
> Support configurable data consistency level
> -------------------------------------------
>
> Key: HDDS-3306
> URL: https://issues.apache.org/jira/browse/HDDS-3306
> Project: Hadoop Distributed Data Store
> Issue Type: Improvement
> Reporter: Sammi Chen
> Priority: Major
>
> Currently，Ozone provides strong data consistency. On data write, Ozone client uses RaftProtos.ReplicationLevel.ALL_COMMITTED which guarantees that the data is persisted to all three datanodes disk before ack the write finish. On data read, if topology is enabled, client will choose the closest datanode to read from. If topology is disabed, then client will always read from leader datanode.
> In some cases, user can tolerate weaker data consistency. They want to balance data consistency with read/write throughput, just as some of our customer required.
> So this issue is to propose a client side configurable consistency level, something like Apache cassandra provides, but not that complicated. The consistency level will be a write and read combination, for example，
> 1. strong consistency, write: ALL, read:any
> 2. strong consistency-favor write throughput, write: majority, read:leader
> 3. evental consistency, write: majority, read: any
> 4. strong consistency-no data safety guarantee，write:leader, read: leader
> 5. evental consistency-no data safety guarantee，write: leader, read:any
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