Stack - Not at all!

On Sat, Sep 22, 2012 at 12:13 AM, Stack <[email protected]> wrote:
> @Harsh Mind if fold the below into the refguide?
> St.Ack
>
> On Fri, Sep 21, 2012 at 10:37 AM, Harsh J <[email protected]> wrote:
>> This is what I would consider a simple-enough, sane networking setup
>> (and can assert that it works very well):
>>
>> [NOTE: This is for simple, small clusters built by folks who are much
>> too new to networking/haven't too much time. Of course, if you know
>> what your DNS setup and resolution ought to look like, ignore this!]
>>
>> 1. A loopback address entry must exist in /etc/hosts. This must never
>> be removed. "127.0.0.1 localhost.localdomain localhost" as the first
>> line is an absolute, whether your services are going to utilize it, or
>> not.
>>
>> 2. If you are looking at a small cluster and feel OK with just using
>> /etc/hosts, then each of your hosts must be present in the /etc/hosts
>> file used in the cluster. A line that goes "EXT.ERN.AL.IP
>> host01.domain host01", repeated properly for each host in the cluster
>> every node should know about (including itself, more importantly),
>> must exist.
>>
>> 3. The (1) and (2) completes your /etc/hosts setup and may in the end
>> look like this on ALL nodes, for an example (Yes, you may rsync/rdist
>> it across):
>>
>> 127.0.0.1 localhost.localdomain localhost
>> 5.1.0.1 node01.cluster node01
>> 5.1.0.2 node02.cluster node02
>> 5.1.0.3 node03.cluster node03
>>
>> [NOTE: The IPs must come from the external NIC interface (eth0, etc.)
>> address reported on each node via "ifconfig". I'll leave IP-assignment
>> and DHCP usage outside of these guidelines.]
>>
>> 4. The /etc/nsswitch.conf must have, for its hosts entry, the config
>> "hosts: files dns". This is usually the default - but ensure it is so
>> on all nodes.
>>
>> 5. (3) and (4) done now makes sure that when resolution is demanded,
>> the /etc/hosts file is what will be used, and that the /etc/hosts file
>> is a good piece now.
>>
>> 6. Next step is to make sure that "hostname -f" and "hostname -s"
>> report proper values on the whole cluster, for each node. The hostname
>> of a machine is vital to be set to match the entry we refer to it as,
>> via the /etc/hosts file. Know that the /etc/hosts file is a lookup
>> file but the hostname comes from the OS itself, when self-queried by
>> applications and tools.
>>
>> 7. For CentOS/RH/Fedora/etc. kinda distros, see
>> http://www.electrictoolbox.com/changing-hostname-centos/ (File:
>> /etc/sysconfig/network, config name HOSTNAME). For Ubuntu/Debian/etc.
>> kinda distros, see
>> http://www.ducea.com/2006/08/07/how-to-change-the-hostname-of-a-linux-system/
>> for one example (File: /etc/hostname, one line simple entry there).
>>
>> 8. Once the hostnames config on the OS match the corresponding node
>> name defined in /etc/hosts, the "hostname -f" should, on node1, report
>> "node01.cluster" and "hostname -s" should report "node01".
>>
>> 9. With (5) and (8) properly done now, stuff will work fine. Begin
>> your Hadoop/HBase configs.
>>
>> HTH some folks building out their new, small clusters. I personally
>> used bind9 on the first system I built, but I had way too much time
>> then to sit down and debug whitespace issues :)
>>
>> On Fri, Sep 21, 2012 at 10:06 PM, Alberto Cordioli
>> <[email protected]> wrote:
>>> Ok.
>>> I'm so sorry to tell you that probably HBase won't work!! :(
>>>
>>> Il giorno 21/set/2012 18.05, "Artem Ervits" <[email protected]> ha scritto:
>>>
>>>> I removed the reference to 127.0.0.1 from every node. Hadoop started as
>>>> necessary and I didn't test hbase yet.
>>>>
>>>>
>>>>
>>>> Artem Ervits
>>>> Data Analyst
>>>> New York Presbyterian Hospital
>>>>
>>>> ----- Original Message -----
>>>> From: Alberto Cordioli [mailto:[email protected]]
>>>> Sent: Friday, September 21, 2012 10:56 AM
>>>> To: [email protected] <[email protected]>
>>>> Subject: Re: Problem with Hadoop and /etc/hosts file
>>>>
>>>> Artem, it's the exact problem I have.
>>>> How did you solve it?
>>>>
>>>> Alberto
>>>>
>>>> On 21 September 2012 14:18, Artem Ervits <[email protected]> wrote:
>>>> > Actually, it is an hbase question. I faced same issue when I was testing
>>>> recovery with hadoop 1 and I had a semi finished hbase cluster setup. The
>>>> start up guide for hbase says to add 127.0.0.1 so when I did that on
>>>> another node and started hadoop using that node as name node, hadoop would
>>>> only see that node running on localhost and not on the static ip. The
>>>> datanodes would not see the name node either. It is kind of confusing that
>>>> hadoop wants it one way and hbase requires it the way hadoop won't work.
>>>> >
>>>> >
>>>> > Artem Ervits
>>>> > Data Analyst
>>>> > New York Presbyterian Hospital
>>>> >
>>>> > ----- Original Message -----
>>>> > From: Stack [mailto:[email protected]]
>>>> > Sent: Tuesday, September 18, 2012 01:08 PM
>>>> > To: [email protected] <[email protected]>
>>>> > Subject: Re: Problem with Hadoop and /etc/hosts file
>>>> >
>>>> > On Tue, Sep 18, 2012 at 12:01 AM, Alberto Cordioli
>>>> > <[email protected]> wrote:
>>>> >> Sorry, maybe I didn't explain well.
>>>> >> I don't know hot to set up rDNS. I'd just know if this problem could
>>>> >> generate the error I reported in the first post (since I get in any
>>>> >> case the correct results).
>>>> >>
>>>> >
>>>> > No need to apologize.  I'm just suggesting that probably better lists
>>>> > for figuring how to set up your networking.  You could start with
>>>> > this? http://en.wikipedia.org/wiki/Reverse_DNS_lookup
>>>> >
>>>> > St.Ack
>>>> >
>>>> >
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>>>>
>>>>
>>>> --
>>>> Alberto Cordioli
>>>>
>>>>
>>>> --------------------
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>>>> --------------------
>>>>
>>>> This electronic message is intended to be for the use only of the named
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>>>>
>>
>>
>>
>> --
>> Harsh J



-- 
Harsh J

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