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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: Region server crash?
Date Thu, 22 Sep 2011 17:44:21 GMT
That question is sort of orthogonal to the first one... Please create
a new thread if you want to change the subject.

HBase uses the DFSClient, for example if HBase needs to open a file it
needs to talk to the NN first (through the DFSClient, HBase doesn't
really know what's going on).

J-D

On Wed, Sep 21, 2011 at 2:06 AM, shanmuganathan.r
<shanmuganathan.r@zohocorp.com> wrote:
> Hi Jack,
>
>            I understood this concept. The DFS client is directly connected to the
datanodes in hdfs and perform the read/write block data with communicate with the namenode
by client protocol . Is there is no direct involvement of
>
>
>  namenode in the HBase operation ?
>
> Thanks
>
> R.Shanmuganathan
>
>
>
> ---- On Wed, 21 Sep 2011 12:55:37 +0530 Jack Levin&lt;magnito@gmail.com&gt; wrote
----
>
>
> The master will detect that RS is down by periodically checking a
> zookeeper ( it will say in the master log, znode expired ). After, it
> will check to see if there is anything in /hbase/.logs directory for
> that region server, if something is found, master will replay the log
> records and 'push' them into region directories, when master is done,
> the 'unopened' regions will be opened by the rest of the region
> servers and all regions that were down will be back online.
>
> -Jack
>
> On Wed, Sep 21, 2011 at 12:21 AM, shanmuganathan.r
> &lt;shanmuganathan.r@zohocorp.com&gt; wrote:
> &gt; Hi All,
> &gt;
> &gt;            I am running the HBase in fully distributed mode. I used the
HBase 0.90.2 version . I have one doubt , that one is what will happen when the Region server
is crashed ?
> &gt;
> &gt;
> &gt; If the one region is managed by one region server then what will happen after
the crash of the region server?
> &gt;
> &gt; Thanks in Advance....
> &gt;
> &gt;
> &gt; Regards
> &gt;
> &gt;
> &gt; R.Shanmuganathan
> &gt;
> &gt;
> &gt;
>
>

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