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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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Harsh J 2012-12-20, 17:48
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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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Re: Question about HA and Federation
Harsh J 2012-12-20, 18:26
Btw, you can co-locate NameNodes (unique namespace ones) onto the same
machine if you need to - the configs easily allow this via rpc/http
port specifiers.

On Thu, Dec 20, 2012 at 11:33 PM, ESGLinux <[EMAIL PROTECTED]> wrote:
> Thank you very much,
>
> your answer have clarified me these concepts very much,
>
> I didn't understand how could I mix HA and Federation and how many nodes I
> need....
>
> Kind Regards,
>
> ESGLinux,
>
> 2012/12/20 Harsh J <[EMAIL PROTECTED]>
>>
>> Yes I think its safe to say that - sorry that I missed out SNNs in my
>> first response (I counted only the regular serving namenodes) :)
>>
>> On Thu, Dec 20, 2012 at 11:25 PM, ESGLinux <[EMAIL PROTECTED]> wrote:
>> > Hi again,
>> >
>> > So finally the number of nodes are these:
>> >
>> > 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 Secondary NameNode
>> > 1 NameNode for NS3 + 1 Secondary NameNode
>> >
>> > We can say that we need 2 nodes per NameSpace, is that true?
>> >
>> > Thanks,
>> >
>> > ESGLinux
>> >
>> >
>> >
>> > 2012/12/20 Harsh J <[EMAIL PROTECTED]>
>> >>
>> >> 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

Harsh J