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From Mohammad Tariq <donta...@gmail.com>
Subject Re: disable table
Date Thu, 27 Sep 2012 08:10:33 GMT
Hello Mohit,

    It should be /hbase/hbase/table/SESSIONID_TIMELINE..Apologies for the
typo. For rest of the things, I feel Ramkrishna sir has provided a good and
proper explanation. Please let us know if you still have any doubt or
question.

Ramkrishna.S.Vasudevan : You are welcome sir. It's my pleasure to share
space with you people.

Regards,
    Mohammad Tariq



On Thu, Sep 27, 2012 at 9:59 AM, Ramkrishna.S.Vasudevan <
ramkrishna.vasudevan@huawei.com> wrote:

> Hi Mohith
> First of all thanks to Tariq for his replies.
>
> Just to add on,
> Basically HBase  uses the Zookeeper to know the status of the cluster like
> the no of tables enabled, disabled and deleted.
> Enabled and deleted states are handled bit different in the 0.94 version.
>
> ZK is used for various region assignments.
>
> Also the ZK is used to track the Active master and standby master.
>
> As you understand correctly that the master is responsible for the overall
> maintenance of the no of tables and their respective states, it seeks the
> help of ZK to do it and that is where the states are persisted.
>
> Also there are few cases where the enable and disable table are having some
> issues due to some race conditions in the 0.92 versions, In the latest
> version we are trying to resolve them.
> You can attach the master and RS logs to identify exactly what caused this
> problem in your case which will be really help ful so that I can be fixed
> in
> the kernel.
>
> Regards
> Ram
>
> > -----Original Message-----
> > From: Mohit Anchlia [mailto:mohitanchlia@gmail.com]
> > Sent: Thursday, September 27, 2012 5:09 AM
> > To: user@hbase.apache.org
> > Subject: Re: disable table
> >
> > I did /hbase/table/SESSIONID_TIMELINE and that seem to work. I'll
> > restart
> > hbase and see if it works.
> >
> > One thing I don't understand is why is zookeeper holding information
> > about
> > this table if it is enabled or disabled? Wouldn't this information be
> > with
> > master?
> >
> > On Wed, Sep 26, 2012 at 4:27 PM, Mohit Anchlia
> > <mohitanchlia@gmail.com>wrote:
> >
> > > I don't see path like /hbase/SESSIONID_TIMELINE
> > > This is what I see
> > >
> > > [zk: pprfdaaha303:5181(CONNECTED) 5] ls /hbase/table
> > > [SESSIONID_TIMELINE]
> > > [zk: pprfdaaha303:5181(CONNECTED) 6] get /hbase/table
> > >
> > > cZxid = 0x1000000fe
> > > ctime = Mon Sep 10 15:31:45 PDT 2012
> > > mZxid = 0x1000000fe
> > > mtime = Mon Sep 10 15:31:45 PDT 2012
> > > pZxid = 0x5000008f1
> > > cversion = 3
> > > dataVersion = 0
> > > aclVersion = 0
> > > ephemeralOwner = 0x0
> > > dataLength = 0
> > > numChildren = 1
> > >
> > >  On Wed, Sep 26, 2012 at 3:57 PM, Mohammad Tariq
> > <dontariq@gmail.com>wrote:
> > >
> > >> In order to delete a znode you have to go to the ZK shell and issue
> > the
> > >> "delete" command along with the required path. For example :
> > >> delete /hbase/SESSIONID_TIMELINE. For detailed info you can visit
> > the ZK
> > >> homepage at : zookeeper.apache.org
> > >>
> > >> Actually when we try to fetch data from an Hbase table, the client
> > or app
> > >> first contacts the ZK to get the location of server holding the
> > >> -ROOT- table. From this we come to know about the server hosting the
> > >> .META.
> > >> table. This tells us the location of the server which actually holds
> > the
> > >> rows of interest. Because of some reasons the znode which was
> > holding this
> > >> info has either faced some catastrophe or lost the info associated
> > with
> > >> this particular table. Or sometimes the znode remains unable to keep
> > >> itself
> > >> updated with the latest changes. That could also be a probable
> > reason. We
> > >> should always keep in mind that ZK is the centralized service that
> > >> actually
> > >> coordinating everything behind the scene. As a result, any problem
> > to the
> > >> ZK quorum means problem with Hbase custer.
> > >>
> > >> Regards,
> > >>     Mohammad Tariq
> > >>
> > >>
> > >>
> > >> On Thu, Sep 27, 2012 at 3:39 AM, Mohit Anchlia
> > <mohitanchlia@gmail.com
> > >> >wrote:
> > >>
> > >> > Thanks! I do see Inconsistency. How do I remove the znode. And
> > also
> > >> could
> > >> > you please help me understand how this might have happened?
> > >> >
> > >> >
> > >> > ERROR: Region
> > >> >
> > SESSIONID_TIMELINE,,1348689726526.0e200aace5e81cead8d8714ed8076050. not
> > >> > deployed on any region server.
> > >> >
> > >> >
> > >> > On Wed, Sep 26, 2012 at 2:36 PM, Mohammad Tariq
> > <dontariq@gmail.com>
> > >> > wrote:
> > >> >
> > >> > > A possible reason could be that the znode associated with this
> > >> particular
> > >> > > table is not behaving properly. In such case, you can try the
> > >> following:
> > >> > >
> > >> > > Stop Hbase
> > >> > > Stop ZK
> > >> > > Take a backup of ZK data
> > >> > > Restart ZK
> > >> > > Remove the znode
> > >> > > Start Hbase again
> > >> > >
> > >> > > After this hopefully your table would be enabled.
> > >> > >
> > >> > > Regards,
> > >> > >     Mohammad Tariq
> > >> > >
> > >> > >
> > >> > >
> > >> > > On Thu, Sep 27, 2012 at 2:59 AM, Mohammad Tariq
> > <dontariq@gmail.com>
> > >> > > wrote:
> > >> > >
> > >> > > > Yes. Also have a look at the logs of the problematic region
if
> > hbck
> > >> > shows
> > >> > > > any inconsistency.
> > >> > > >
> > >> > > > Regards,
> > >> > > >     Mohammad Tariq
> > >> > > >
> > >> > > >
> > >> > > >
> > >> > > > On Thu, Sep 27, 2012 at 2:55 AM, Mohit Anchlia <
> > >> mohitanchlia@gmail.com
> > >> > > >wrote:
> > >> > > >
> > >> > > >> Which node should I look at for logs? Is this the master
> > node? I'll
> > >> > try
> > >> > > >> hbck.
> > >> > > >>
> > >> > > >> On Wed, Sep 26, 2012 at 2:19 PM, Mohammad Tariq <
> > >> dontariq@gmail.com>
> > >> > > >> wrote:
> > >> > > >>
> > >> > > >> > Hello Mohit,
> > >> > > >> >
> > >> > > >> >     Try hbck once and see if it shows any inconsistency.
> > Also,
> > >> you
> > >> > can
> > >> > > >> try
> > >> > > >> > restarting your cluster and deleting the table
again.
> > Having a
> > >> look
> > >> > at
> > >> > > >> the
> > >> > > >> > logs could also be useful.
> > >> > > >> >
> > >> > > >> > Regards,
> > >> > > >> >     Mohammad Tariq
> > >> > > >> >
> > >> > > >> >
> > >> > > >> >
> > >> > > >> > On Thu, Sep 27, 2012 at 2:24 AM, Mohit Anchlia
<
> > >> > > mohitanchlia@gmail.com
> > >> > > >> > >wrote:
> > >> > > >> >
> > >> > > >> > > When I try to disable table I get:
> > >> > > >> > >
> > >> > > >> > >  hbase(main):011:0> disable 'SESSIONID_TIMELINE'
> > >> > > >> > > ERROR: org.apache.hadoop.hbase.TableNotEnabledException:
> > >> > > >> > > org.apache.hadoop.hbase.TableNotEnabledException:
> > >> > SESSIONID_TIMELINE
> > >> > > >> > > Here is some help for this command:
> > >> > > >> > > Start disable of named table: e.g. "hbase>
disable 't1'"
> > >> > > >> > >
> > >> > > >> > > But then I try to enable I get:
> > >> > > >> > >
> > >> > > >> > > hbase(main):012:0> enable 'SESSIONID_TIMELINE'
> > >> > > >> > > ERROR: org.apache.hadoop.hbase.TableNotDisabledException:
> > >> > > >> > > org.apache.hadoop.hbase.TableNotDisabledException:
> > >> > > SESSIONID_TIMELINE
> > >> > > >> > > Here is some help for this command:
> > >> > > >> > > Start enable of named table: e.g. "hbase>
enable 't1'"
> > >> > > >> > >
> > >> > > >> > > I've tried flush, major_compaction also. I
tseems it's
> > stuck in
> > >> > > >> > > inconsistent state. Could someone point me
to correct
> > >> direction? I
> > >> > > am
> > >> > > >> > using
> > >> > > >> > > 92.1
> > >> > > >> > >
> > >> > > >> >
> > >> > > >>
> > >> > > >
> > >> > > >
> > >> > >
> > >> >
> > >>
> > >
> > >
>
>

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