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 > >>> > >>> On Wed, Nov 30, 2011 at 3:49 PM, Rita <[email protected]> wrote: > >>>> Hello, > >>>> > >>>> > >>>> Previously, I assigned 5 servers as part of the zookeeper quorum. > >>>> Everything works fine but I was hard coding these 5 servers > everywhere and > >>>> I was thinking of creating a dns entry called appquorum which will > always > >>>> return these 5 servers IPs. > >>>> > >>>> Any thoughts about this? > >>>> > >>>> > >>>> > >>>> -- > >>>> --- Get your facts first, then you can distort them as you please.-- >
