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Posted to issues@ozone.apache.org by "Prashant Pogde (Jira)" <ji...@apache.org> on 2020/10/23 23:22:00 UTC
[jira] [Commented] (HDDS-4342) Add DataNode state and transitions
for a node going through upgrade
[ https://issues.apache.org/jira/browse/HDDS-4342?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17219968#comment-17219968 ]
Prashant Pogde commented on HDDS-4342:
--------------------------------------
A typical SCM sequence for driving datanodes through upgrade would be
something like following :
- client sends Finalize
- SCM moves to Finalizing states. If SCM crashes, and it comes up
it will always restart from this state.
- SCM disallows new pipeline creation, SCM in safe mode
(SCM Freeze for new pipeline)
- SCM closes existing pieplines
- SCM updates MLV = SLV if not already so. Update on-disk MLV state.
- SCM moves all data nodes to HEALTHY_READONLY state. Please note that
initial state for all data node is HEALTHY_READONLY. For data nodes
to move from HEALTHY_READONLY -> HEALTHY, they need to send atleast
one heartbeat where DN.MLV == SCM.MLV
- SCM waits for few heartbeats
- SCM allows new pipeline creation (SCM thaw for new pipeline creation).
New Pipelines can be created if enough HEALTHY data nodes are found.
- If SCM comes across any data node heart beat with DN.MLV < SCM.MLV => SCM sends
that data node finalize command
======================================================================
As part of this, we would be introducing a new state HEALTHY-READONLY in DataNode state machine maintained in SCM .
This Jira will be used to make changes in the datanode state machine.
> Add DataNode state and transitions for a node going through upgrade
> -------------------------------------------------------------------
>
> Key: HDDS-4342
> URL: https://issues.apache.org/jira/browse/HDDS-4342
> Project: Hadoop Distributed Data Store
> Issue Type: Sub-task
> Reporter: Prashant Pogde
> Assignee: Prashant Pogde
> Priority: Major
>
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