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Date: Thu, 24 Mar 2011 23:32:06 +0000 (UTC)
From: "Jean-Daniel Cryans (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-3681) Check the sloppiness of the region
 load before balancing
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    [ https://issues.apache.org/jira/browse/HBASE-3681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13011004#comment-13011004 ] 

Jean-Daniel Cryans commented on HBASE-3681:
-------------------------------------------

Some comments:

 - I think the ifs in the new constructor aren't written consistently with the rest of the code. Usually we either do brackets or one-line ifs and this is neither.
 - I wouldn't reuse the min/max since they don't have the same meaning.
 - The comment "so that behavior is consistent with that of 0.90.1." is true but I don't think it belongs in there, since it will go stale very fast. Just saying that here is enough IMO.
 - I think for 0.92 we could set the slop to something like 0.1 or 0.2, but keep it at 0 for 0.90.1. Regarding that, Stack moved this issue to 0.92 but he agreed we can move it back into 0.90.2 since 1) we need it at SU and 2) it's going to be disabled by default.

> Check the sloppiness of the region load before balancing
> --------------------------------------------------------
>
>                 Key: HBASE-3681
>                 URL: https://issues.apache.org/jira/browse/HBASE-3681
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.90.1
>            Reporter: Jean-Daniel Cryans
>            Assignee: Ted Yu
>             Fix For: 0.92.0
>
>         Attachments: hbase-3681-v2.txt, hbase-3681.txt
>
>
> Per our discussion at the hackathon today, it seems that it would be more helpful to add a sloppiness check before doing the normal balancing.
> The current situation is that the balancer always tries to get the region load even, meaning that there can be some very frequent regions movement.
> Setting the balancer to run less often (like every 4 hours) isn't much better since the load could get out of whack easily.
> This is why running the normal balancer frequently, but first checking for some sloppiness in the region load across the RS, seems like a more viable option.

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