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Posted to user@hbase.apache.org by "shanmuganathan.r" <sh...@zohocorp.com> on 2011/09/21 09:21:35 UTC
Region server crash?
Hi All,
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 ?
If the one region is managed by one region server then what will happen after the crash of the region server?
Thanks in Advance....
Regards
R.Shanmuganathan
Re: Region server crash?
Posted by Jean-Daniel Cryans <jd...@apache.org>.
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
<sh...@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<magnito@gmail.com> 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
> <shanmuganathan.r@zohocorp.com> wrote:
> > Hi All,
> >
> > 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 ?
> >
> >
> > If the one region is managed by one region server then what will happen after the crash of the region server?
> >
> > Thanks in Advance....
> >
> >
> > Regards
> >
> >
> > R.Shanmuganathan
> >
> >
> >
>
>
Re: Region server crash?
Posted by "shanmuganathan.r" <sh...@zohocorp.com>.
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<magnito@gmail.com> 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
<shanmuganathan.r@zohocorp.com> wrote:
> Hi All,
>
> 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 ?
>
>
> If the one region is managed by one region server then what will happen after the crash of the region server?
>
> Thanks in Advance....
>
>
> Regards
>
>
> R.Shanmuganathan
>
>
>
Re: Region server crash?
Posted by Jack Levin <ma...@gmail.com>.
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
<sh...@zohocorp.com> wrote:
> Hi All,
>
> 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 ?
>
>
> If the one region is managed by one region server then what will happen after the crash of the region server?
>
> Thanks in Advance....
>
>
> Regards
>
>
> R.Shanmuganathan
>
>
>