[jira] [Commented] (ACCUMULO-4353) Stabilize tablet assignment during transient failure

["Keith Turner (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-4353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15358209#comment-15358209 ] 

Keith Turner commented on ACCUMULO-4353:
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I am in favor of what Shawn has done in his patch over what was proposed in ACCUMULO-1454.  I think whats in this patch is much easier to use.   One thing I was trying to accomplish in the proposal for ACCUMULO-1454 was to minimize down time by allowing a new tserver to be started on a node and everything migrated before killing the old one.   This may minimize down time, but I think it would be very complex to actually do this in practice as Shawn pointed out.

> Stabilize tablet assignment during transient failure
> ----------------------------------------------------
>
>                 Key: ACCUMULO-4353
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4353
>             Project: Accumulo
>          Issue Type: Improvement
>            Reporter: Shawn Walker
>            Assignee: Shawn Walker
>            Priority: Minor
>          Time Spent: 2h 10m
>  Remaining Estimate: 0h
>
> When a tablet server dies, Accumulo attempts to reassign the tablets it was hosting as quickly as possible to maintain availability.  If multiple tablet servers die in quick succession, such as from a rolling restart of the Accumulo cluster or a network partition, this behavior can cause a storm of reassignment and rebalancing, placing significant load on the master.
> To avert such load, Accumulo should be capable of maintaining a steady tablet assignment state in the face of transient tablet server loss.  Instead of reassigning tablets as quickly as possible, Accumulo should be await the return of a temporarily downed tablet server (for some configurable duration) before assigning its tablets to other tablet servers.



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