Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Hadoop, mail # user - Question about HA and Federation


Copy link to this message
-
Re: Question about HA and Federation
ESGLinux 2012-12-20, 18:03
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
> >> >> >
> >> >> >
> >> >> >
> http://hadoop.apache.org/docs/r0.23.0/hadoop-yarn/hadoop-yarn-site/Federation.html
> >> >> >
> >> >> > Thanks in advance
> >> >> >
> >> >> > ESGLinux
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> Harsh J
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Harsh J
> >
> >
>
>
>
> --
> Harsh J
>