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Posted to issues@ozone.apache.org by "Wei-Chiu Chuang (Jira)" <ji...@apache.org> on 2025/04/25 04:43:00 UTC
[jira] [Commented] (HDDS-12578) Ozone on CRAQ
[ https://issues.apache.org/jira/browse/HDDS-12578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17947230#comment-17947230 ]
Wei-Chiu Chuang commented on HDDS-12578:
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Do you mean Ratis Streaming?
I'm not sure having chain replication is a requirement for rolling upgrade. cc [~erose] [~pifta] does ZDU require it?
> Ozone on CRAQ
> -------------
>
> Key: HDDS-12578
> URL: https://issues.apache.org/jira/browse/HDDS-12578
> Project: Apache Ozone
> Issue Type: Wish
> Reporter: Ivan Andika
> Assignee: Ivan Andika
> Priority: Major
>
> This is just a long-term wish to explore Chain Replication or CRAQ on Ozone.
> Currently Ozone supports Raft based write pipeline and EC. From the Data replication spectrum ([https://transactional.blog/blog/2024-data-replication-design-spectrum]), these two pipelines cover the Leader-based (Raft based write pipeline) and Quorum-based (EC) replication algorithm. CRAQ falls under Reconfiguration-based replication algorithms.
> We can consider supporting CRAQ pipelines on Ozone. As mentioned in discussion [https://github.com/apache/ozone/discussions/6870#discussioncomment-9907706], chained replication might be needed for rolling upgrade support. Although CRAQ promised higher bandwidth, higher read performance, and strong consistency, there are some drawbacks such as higher write latency (since all writes need to propagate to the tail), higher downtime during node failure (waiting for the control plane to reconfigure the chains), etc.
> The wish comes from the recent DeepSeek 3FS distributed file system that uses CRAQ as its main write pipeline ([https://github.com/deepseek-ai/3FS/blob/main/docs/design_notes.md]). Other system such as Meta's Delta ([https://engineering.fb.com/2022/05/04/data-infrastructure/delta/]) also uses CRAQ.
> Since it is a Reconfiguration-based replication algorithms, there might be a need to support ZooKeeper-like semantics on top of Ratis or Raft in SCM HA, similar to Clickhouse Keeper ([https://clickhouse.com/clickhouse/keeper]) or Meta's Zelos (https://engineering.fb.com/2022/06/08/developer-tools/zelos/)
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