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From Denis <de...@camfex.cz>
Subject Re: How to get pre-ACCUMULO-1585 behaviour (use IPs, not hostnames)
Date Sun, 06 Sep 2015 07:29:57 GMT
I am afraid of bugs caused by introducing DNS-server:
* if could easily get out of sync with hostname-ip correspondence on
the nodes (the host name a node has could be resolved by DNS-server to
IP or another node, or even worse: a node could be started with
hostname like "ubuntu.com").
* two or more DNS-server (as one is the SPOF) could get out of sync.
* DNS-servers could be unreachable due to overload caused by other
clients (it happens quite often in dev environment).
* DNS-resolving introduces additional delay which could be slow due to
UDP-packet loss and retry.

Perhaps, a script maintaining /etc/hosts on all nodes or solutions
like Consul.io would address some of these problems.

I like your solution with --address command line switch more than
HDFS's property
"dfs.namenode.datanode.registration.ip-hostname-check", as it allows
to use nodes with more than 1 IP.


On 9/6/15, Josh Elser <josh.elser@gmail.com> wrote:
> FYI, there is reasoning behind doing this in respect to the larger
> Hadoop community. When you run with Kerberos, things will not work at
> all without proper hostnames. There are lots of cases where dealing with
> hostnames is easier than IPs (e.g. what happens if the physical host you
> run the namenode on dies and you need to transition it to a different
> node -- IPs make this much more difficult).
>
> That said, if there is something we can do that will make this easier
> for your situation, let's give it some thought. I don't think I realized
> that things were actually broken with IPs, just that we strongly
> recommend using hostnames instead.
>
> Denis wrote:
>> I found the answer in the sources: start the daemons with "--address
>> 10.x.x.x" command line switch.
>>
>> I am trying to install Accumulo 1.7 (I have experience with early
>> versions) and found if inconvenient the Accumulo now requires
>> hostnames;
>> I do not like the idea to maintain the configuration of a DNS-server
>> (or hostname-IP correspondence in /etc/hosts of all the servers on all
>> the servers)
>>
>> On 9/5/15, Josh Elser<josh.elser@gmail.com>  wrote:
>>> I'm not entirely sure if I understand your question. Are you running
>>> Accumulo 1.5 and having problems running Accumulo w/ only IP addresses?
>>>
>>> It's not readily apparent to me what changes were actually made in the
>>> tickets as it appears JIRA didn't pick up the commit reference.
>>>
>>> For as long as I can remember, the network interface (e.g. 127.0.0.1,
>>> localhost, `hostname -a`, `hostname -f`) you provide in
>>> ${ACCUMULO_CONF_DIR}/{masters,monitors,slaves,gc,tracers} should
>>> ultimately determine what is advertised in ZooKeeper. Maybe that's the
>>> change Eric made...
>>>
>>> Denis wrote:
>>>> Hello
>>>>
>>>> What would be the recommended way to win the pre-ACCUMULO-1585
>>>> behavior, i.e IPs of services in ZooKeeper and no need for DNS not
>>>> reverse DNS?
>

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