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HBase >> mail # user >> zookeeper quorum verification


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Re: zookeeper quorum verification
Thanks for the nice responses and advice.

To sum up this thread

This will not work,

$ host roundrobindnsentry
roundrobindnsentry has address 192.168.0.2
roundrobindnsentry has address 192.168.0.5
roundrobindnsentry has address 192.168.0.6
$ host roundrobindnsentry
roundrobindnsentry has address 192.168.0.5
roundrobindnsentry has address 192.168.0.6
roundrobindnsentry has address 192.168.0.2
Ín your hbase-site.xml

<property>
      <name>hbase.zookeeper.quorum</name>
      <value>roundrobindnsentry</value>
      </description>
    </property>
This will not work because when you start up the hbase cluster it will
complain the zookeeper is already running. Basically it will get confused
because of the round robin DNS entries.

However,  this WILL work if in your application you set, roundrobingdns
entry.

On Sat, Dec 3, 2011 at 8:09 PM, Shrijeet Paliwal <[EMAIL PROTECTED]>wrote:

> >>Now any HBase client that needs to connect to zookeeper, can talk to
> quorum via "zookeeper-quorum.example.com"
>
> Must add the reason above works is zookeeper uses  InetAddress.getAllByName
> <
> http://docs.oracle.com/javase/1.3/docs/api/java/net/InetAddress.html#getAllByName(java.lang.String)
> >to
> build the server address list
>
> On Sat, Dec 3, 2011 at 5:06 PM, Shrijeet Paliwal <[EMAIL PROTECTED]
> >wrote:
>
> > Suraj,
> > Combine what J-D & David said. For example in our case
> >
> >    1. We let HBase manage zookeeper
> >    2. Set the config in hbase-site.xml the way David mentioned
> >    :
> <value>0.zookeeper,1.zookeeper,2.zookeeper,3.zookeeper,4.zookeeper</value>
> >    3. Also have a DNS entry "zookeeper-quorum.example.com" with multiple
> >    IPs (all mentioned above) resolving to this entry
> >    4. Now any HBase client that needs to connect to zookeeper, can talk
> >    to quorum via "zookeeper-quorum.example.com"
> >
> > One might think why we cant have hbase-site use ""
> > zookeeper-quorum.example.com" as well. My understanding is when you
> start
> > a zookeeper daemon on a server, the hbase managed zookeeper service will
> > fetch the the default host name using hadoop's DNS.getDefaultHost method.
> > The hostname returned may or may not find a match in the server list you
> > mentioned in hbase-site.xml. If does not match you get the error
> mentioned
> > here http://wiki.apache.org/hadoop/Hbase/Troubleshooting#A9.
> >
> > For example, in our case zookeeper host has two hostnames associated with
> > default ethernet interface. First name is host.domain.com and second is
> > the special DNS entry I talked about in (4). The DNS.getDefaultHost
> returns
> > host.domain.com and zookeeper fails to start.
> >
> > I would be interested if some one has a different way of handling the
> > situation I described.
> >
> > On Sat, Dec 3, 2011 at 4:45 PM, Suraj Varma <[EMAIL PROTECTED]> wrote:
> >
> >> Yes - this makes sense. But, I thought what Rita suggested was a
> >> single appquorum dns entry ... which was surprising.
> >>
> >> Hence my question.
> >> --Suraj
> >>
> >> On Sat, Dec 3, 2011 at 10:40 AM, Dave Barr <[EMAIL PROTECTED]> wrote:
> >> > What we do is make N.zookeeper.$DC.$DOMAIN entries in DNS.  We have
> >> > one ZK cluster per DC.  Our configs then just point to
> >> >
> >> >
> >>
> <value>0.zookeeper,1.zookeeper,2.zookeeper,3.zookeeper,4.zookeeper</value>
> >> >
> >> > --Dave
> >> >
> >> > On Sat, Dec 3, 2011 at 6:15 AM, Suraj Varma <[EMAIL PROTECTED]>
> >> wrote:
> >> >> J-D:
> >> >> Did you mean that a _single_ dns entry returns all five ips belonging
> >> >> to individual zk nodes?
> >> >>
> >> >> Is this used only by "clients" ... or even within the cluster?
> >> >> And ... the zk nodes self-identify by IP ... and is this how region
> >> >> server nodes reach out specifically to the "leader" zk node?
> >> >> --Suraj
> >> >>
> >> >>
> >> >> On Wed, Nov 30, 2011 at 4:14 PM, Jean-Daniel Cryans <
> >> [EMAIL PROTECTED]> wrote:
> >> >>> It's pretty much what we do, works well.
> >> >>>
> >> >>> J-D

NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB