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Andrew Purtell reopened HBASE-10528: ------------------------------------ Reopened since we had some reverts. Let's fix the failing test and get this back in. > DefaultBalancer selects plans to move regions onto draining nodes > ----------------------------------------------------------------- > > Key: HBASE-10528 > URL: https://issues.apache.org/jira/browse/HBASE-10528 > Project: HBase > Issue Type: Bug > Affects Versions: 0.94.5 > Reporter: churro morales > Assignee: churro morales > Fix For: 1.0.0, 2.0.0, 1.1.0 > > Attachments: 10528-1.0.addendum, HBASE-10528-0.94.patch, > HBASE-10528-0.98.patch, HBASE-10528.patch, HBASE-10528.v2.patch > > > We have quite a large cluster > 100k regions, and we needed to isolate a > region was very hot until we could push a patch. We put this region on its > own regionserver and set it in the draining state. The default balancer was > selecting regions to move to this cluster for its region plans. > It just so happened for other tables, the default load balancer was creating > plans for the draining servers, even though they were not available to move > regions to. Thus we were closing regions, then attempting to move them to > the draining server then finding out its draining. > We had to disable the balancer to resolve this issue. > There are some approaches we can take here. > 1. Exclude draining servers altogether, don't even pass those into the load > balancer from HMaster. > 2. We could exclude draining servers from ceiling and floor calculations > where we could potentially skip load balancing because those draining servers > wont be represented when deciding whether to balance. > 3. Along with #2 when assigning regions, we would skip plans to assign > regions to those draining servers. > I am in favor of #1 which is simply removes servers as candidates for > balancing if they are in the draining state. > But I would love to hear what everyone else thinks. -- This message was sent by Atlassian JIRA (v6.3.4#6332)