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https://issues.apache.org/jira/browse/HDDS-2113?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16927840#comment-16927840
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Stephen O'Donnell commented on HDDS-2113:
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[~nandakumar131] [~anu] [~arpaga] I would appreciate your thoughts on this.
> Update JMX metrics in SCMNodeMetrics for Decommission and Maintenance
> ---------------------------------------------------------------------
>
> Key: HDDS-2113
> URL: https://issues.apache.org/jira/browse/HDDS-2113
> Project: Hadoop Distributed Data Store
> Issue Type: Sub-task
> Components: SCM
> Affects Versions: 0.5.0
> Reporter: Stephen O'Donnell
> Assignee: Stephen O'Donnell
> Priority: Major
>
> Currently the class SCMNodeMetrics exposes JMX metrics for the number of
> HEALTHY, STALE and DEAD nodes.
> It also exposes the disk capacity of the cluster and the amount of space used
> and available.
> We need to decide how we want to display things in JMX when nodes are in and
> entering maintenance, decommissioning and decommissioned.
> We now have 15 states rather than the previous 3, as we can have nodes in:
> * IN_SERVICE
> * ENTERING_MAINTENANCE
> * IN_MAINTENANCE
> * DECOMMISSIONING
> * DECOMMISSIONED
> And in each of these states, nodes can be:
> * HEALTHY
> * STALE
> * DEAD
> The simplest case would be to expose these 15 states directly in JMX, as it
> gives the complete picture, but I wonder if we need any summary JMX metrics
> too?
>
> We also need to consider how to count disk capacity and usage. For example:
> # Do we count capacity and usage on a DECOMMISSIONING node? This is not a
> clear cut answer, as a decommissioning node does not provide any capacity for
> writers in the cluster, but it does use capacity.
> # For a DECOMMISSIONED node, we probably should not count capacity or usage
> # For an ENTERING_MAINTENANCE node, do we count capacity and usage? I
> suspect we should include the capacity and usage in the totals, however a
> node in this state will not be available for writes.
> # For an IN_MAINTENANCE node that is healthy?
> # For an IN_MAINTENANCE node that is dead?
> I would welcome any thoughts on this before changing the code.
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