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Date: Sun, 4 Dec 2011 10:03:32 -0500 Message-ID: Subject: Re: zookeeper quorum verification From: Rita To: user@hbase.apache.org Content-Type: multipart/alternative; boundary=bcaec547cad972e5a204b3458180 X-Virus-Checked: Checked by ClamAV on apache.org --bcaec547cad972e5a204b3458180 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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 =CDn your hbase-site.xml hbase.zookeeper.quorum roundrobindnsentry 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 w= rote: > >>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.getAllByNa= me > < > http://docs.oracle.com/javase/1.3/docs/api/java/net/InetAddress.html#getA= llByName(java.lang.String) > >to > build the server address list > > On Sat, Dec 3, 2011 at 5:06 PM, Shrijeet Paliwal >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 > > : > 0.zookeeper,1.zookeeper,2.zookeeper,3.zookeeper,4.zookeeper > > 3. Also have a DNS entry "zookeeper-quorum.example.com" with multipl= e > > 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 wil= l > > fetch the the default host name using hadoop's DNS.getDefaultHost metho= d. > > The hostname returned may or may not find a match in the server list yo= u > > 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 wi= th > > 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 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 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 > >> > > >> > > >> > 0.zookeeper,1.zookeeper,2.zookeeper,3.zookeeper,4.zookeeper > >> > > >> > --Dave > >> > > >> > On Sat, Dec 3, 2011 at 6:15 AM, Suraj Varma > >> wrote: > >> >> J-D: > >> >> Did you mean that a _single_ dns entry returns all five ips belongi= ng > >> >> 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 < > >> jdcryans@apache.org> wrote: > >> >>> It's pretty much what we do, works well. > >> >>> > >> >>> J-D > >> >>> > >> >>> On Wed, Nov 30, 2011 at 3:49 PM, Rita 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 wil= l > >> always > >> >>>> return these 5 servers IPs. > >> >>>> > >> >>>> Any thoughts about this? > >> >>>> > >> >>>> > >> >>>> > >> >>>> -- > >> >>>> --- Get your facts first, then you can distort them as you > please.-- > >> > > > > > --=20 --- Get your facts first, then you can distort them as you please.-- --bcaec547cad972e5a204b3458180--