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Hadoop >> mail # user >> Question about HA and Federation


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ESGLinux 2012-12-20, 16:30
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Harsh J 2012-12-20, 17:12
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ESGLinux 2012-12-20, 17:39
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Re: Question about HA and Federation
Hi,

To put it simply: If you use a NameNode, you need a SecondaryNameNode.
In HA-mode, a StandbyNameNode acts as a SecondaryNameNode (so you
don't need to run an extra).

Either way, you definitely need the checkpoint operation happening and
being monitored for.

On Thu, Dec 20, 2012 at 11:09 PM, ESGLinux <[EMAIL PROTECTED]> wrote:
> Hi Harsh,
>
> First thank you very much for your answer,
>
> following your example:
>
> You have:
>
> 1 Active NameNode + 1 Passive NameNode (it does the work of the old
> Secondary NameNode) for NS1 NameSpace (these are 2 diferent machines)
> 1 NameNode for NS2
> 1 NameNode for NS3
>
> but what about the Secondary Name Nodes for NS2 and NS3? or I don´t need it?
> perhaps I´m mixing concepts....
>
> Thanks again,
>
> Greetings,
>
> ESGLinux
>
>
>
>
> 2012/12/20 Harsh J <[EMAIL PROTECTED]>
>>
>> Hi ESGLinux,
>>
>> Federation and HA are two distinct features that share some common
>> properties but nothing more. You can turn on HA for any selected
>> Namespace but it is not necessarily needed to be that all Namespaces
>> have HA.
>>
>> Perhaps an example will clear it up for you.
>>
>> I have a local instance that is configured to run several namespaces:
>> ns1, ns2, and ns3 (Federated Namespaces).
>> The namespace ns1 hosts my HBase tables and is critical to me, so I
>> have also turned on HA for this namespace alone.
>> The other two namespaces ns2 and ns3 are used only for regular query
>> jobs so its not yet very important for me to have HA on it. So I run
>> them without HA.
>>
>> Thus I have 4 NameNode processes in my cluster in all, given my design
>> above: (2 NNs under ns1, in HA mode) + (1 NN of ns2) + (1 NN of ns3).
>>
>> On Thu, Dec 20, 2012 at 10:00 PM, ESGLinux <[EMAIL PROTECTED]> wrote:
>> > Hi All,
>> >
>> > I´m going to test a hadoop cluster and I have a doubt about HA and
>> > Federation.
>> >
>> > With federation I Have a NameNode per namespace and with HA I have an
>> > Active
>> > NameNode and a standby NameNode.
>> >
>> > so, as I have sevaral namespaces, do I need an Active NameNode and a
>> > standby
>> > nameNode per namespace?
>> >
>> > I have read this documentation but It´s not clear for me :-(
>> >
>> >
>> > https://ccp.cloudera.com/display/CDH4DOC/Introduction+to+Hadoop+High+Availability
>> >
>> > http://hadoop.apache.org/docs/r0.23.0/hadoop-yarn/hadoop-yarn-site/Federation.html
>> >
>> > Thanks in advance
>> >
>> > ESGLinux
>> >
>>
>>
>>
>> --
>> Harsh J
>
>

--
Harsh J
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ESGLinux 2012-12-20, 17:55
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Harsh J 2012-12-20, 17:57
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ESGLinux 2012-12-20, 18:03
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Harsh J 2012-12-20, 18:26