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https://issues.apache.org/jira/browse/HBASE-11059?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14027174#comment-14027174
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Jimmy Xiang commented on HBASE-11059:
-------------------------------------
[~jeffreyz], thanks a lot for the review.
bq. 1) Rolling restart when turn hbase.assignment.usezk from OFF to ON.
This is not supported. We support rolling restart from ON to OFF, i.e. from
using ZK to not using ZK.
bq. 2) When hbase.assignment.usezk is ON, a region...
This is the existing behavior. Before the master sends region open RPC to RS,
the ZK is already created in proper state. So it's enough to process RITs
recorded in ZK assignment node only.
bq. 3) When a region is opened after master receives region transition response
from RS, could we use checkAndPut to update META...
This is too conservative. The idea is that in the new scheme, the master should
be the source of truth, and have the meta info in memory, that's why we just
check against the info in RegionStates.
bq. 4) Inside postOpenDeployTasks, when reportRegionTransition return false we
don't offline the region in RS.
Good catch. In this case, postOpenDeployTasks should throw an exception so the
region will be offlined. I will handle this in the next patch.
bq. 5) A rare race condition that a RS fails to open a region and it reports to
master as FAILED_OPEN but without firstly changing its internal memory state....
Right. This seems to be an existing issue, right?
> ZK-less region assignment
> -------------------------
>
> Key: HBASE-11059
> URL: https://issues.apache.org/jira/browse/HBASE-11059
> Project: HBase
> Issue Type: Improvement
> Components: master, Region Assignment
> Reporter: Jimmy Xiang
> Assignee: Jimmy Xiang
> Fix For: 0.99.0
>
> Attachments: hbase-11059.patch, hbase-11059_v2.1.patch,
> hbase-11059_v2.2.patch, hbase-11059_v2.patch, zk-less_am.pdf,
> zk-less_assignment.png
>
>
> It seems that most people don't like region assignment with ZK (HBASE-5487),
> which causes many uncertainties. This jira is to support ZK-less region
> assignment. We need to make sure this patch doesn't break backward
> compatibility/rolling upgrade.
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