[
https://issues.apache.org/jira/browse/HBASE-6348?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Duo Zhang resolved HBASE-6348.
------------------------------
Resolution: Not A Problem
We have purged the root table for a long time. Although recently we want to
introduce it back...
> Region assignments should be only allowed edit META hosted on the same
> cluster.
> -------------------------------------------------------------------------------
>
> Key: HBASE-6348
> URL: https://issues.apache.org/jira/browse/HBASE-6348
> Project: HBase
> Issue Type: Task
> Reporter: Jonathan Hsieh
> Priority: Major
>
> We copied hbase file data (root/meta/tables) from one hdfs cluster to
> another, scrubbed it, and then attempted to start the new cluster. We
> noticed that META on the original cluster was being modified with server
> entries from the new cluster.
> Its contrived but here is how it happened.
> First we copied all the data. Then we "scrubbed" META -- we removed all
> region serverinfo cols that pointed to nodes on the original cluster. When
> we started the new cluster, it picked a RS to serve ROOT. Since we had
> scrubbed meta, then the new cluster's master attempted to assign regions to
> other region servers on the new cluster. From the code's point of view this
> all succeeeded -- zk went through transitions, according to the master they
> were assigned. However, we started seeing NotServingRegionExceptions on the
> original cluster.
> The root cause is that ROOT was not scrubbed. The new cluster assigned the
> copy of ROOT to a new cluster RS. Now, when the new cluster attempted to
> modify META, it would read the old ROOT's serverinfo pointer go to the *old
> cluster's regionserver*. The old cluster's regionserer just so happened to
> be still serving META, so the old cluster's META server gladly accepted the
> assignments that included the new cluster's regionserver names.
> At this point we brought down the new cluster (it was getting killed).
> Clients on the old cluster would now go to zk,root,meta, and get pointers to
> the new cluster. NSRE's happened. Unhappyness.
> Long story short, we should have some mechanism to make sure that region
> assignments should be only allowed edit META hosted on the same cluster.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
