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https://issues.apache.org/jira/browse/HBASE-3171?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12983191#action_12983191
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mac fang commented on HBASE-3171:
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+1, in my mind, the -ROOT- table is very important of routing the right 
RegionServer of .META. The whole system could be out-of-service in case the 
Region of SequenceFile of the -ROOT- can NOT be opened. Thus, i quite agree 
that we put the .META. directly into Zookeeper to reduce this. We can avoid one 
case of failure. 

> Drop ROOT and instead store META location(s) directly in ZooKeeper
> ------------------------------------------------------------------
>
>                 Key: HBASE-3171
>                 URL: https://issues.apache.org/jira/browse/HBASE-3171
>             Project: HBase
>          Issue Type: Improvement
>          Components: client, master, regionserver, zookeeper
>            Reporter: Jonathan Gray
>             Fix For: 0.92.0
>
>
> Rather than storing the ROOT region location in ZooKeeper, going to ROOT, and 
> reading the META location, we should just store the META location directly in 
> ZooKeeper.
> The purpose of the root region from the bigtable paper was to support 
> multiple meta regions.  Currently, we explicitly only support a single meta 
> region, so the translation from our current code of a single root location to 
> a single meta location will be very simple.  Long-term, it seems reasonable 
> that we could store several meta region locations in ZK.  There's been some 
> discussion in HBASE-1755 about actually moving META into ZK, but I think this 
> jira is a good step towards taking some of the complexity out of how we have 
> to deal with catalog tables everywhere.
> As-is, a new client already requires ZK to get the root location, so this 
> would not change those requirements in any way.
> The primary motivation for this is to simplify things like CatalogTracker.  
> The way we can handle root in that class is really simple but the tracking of 
> meta is difficulty and a bit hacky.  This hack on tracking of the meta 
> location is what caused one of the bugs over in HBASE-3159.

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