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From "Terry P." <>
Subject Re: Accumulo Standby Master question
Date Wed, 06 Nov 2013 18:12:36 GMT
Ahh thanks Billie, I'll stick with just one monitor then.  Thanks!

On Wed, Nov 6, 2013 at 10:32 AM, Billie Rinaldi <>wrote:

> On Tue, Nov 5, 2013 at 12:51 PM, Josh Elser <> wrote:
>> It looks like you can configure multiple hosts for GC and they'll use
>> ZooKeeper to perform failover (like the master).
>> Tracers -- You can run multiple tracer processes. You likely don't need
>> 1:1 as you run tservers, but you can run a few if you're concerned about
>> it. They're not required for Accumulo operation.
>> Same for the monitor. If you need to have multiple running for failover
>> purposes, it looks like you can specify multiple and it will just launch a
>> monitor on each host you specified. There's no centralize URL you can
>> always hit here. You would have to check each one to find one that was,
>> unless you want to run some sort of reverse-proxy in front of them all.
> I think additional monitors won't work entirely as expected.  The log
> forwarding from the other processes is set up when the processes are
> started, and the logs are only sent to the first host in the monitor file.
>> _obligatory I just looked to source code to come to this conclusion_
>> On 11/5/13, 3:13 PM, Terry P. wrote:
>>> I put my secondary namenode in the masters file for the first time with
>>> this latest Accumulo 1.4.2 cluster deployment so it would run as a
>>> Standby Accumulo Master which I read about in the User Guide.  Recently
>>> had the Master lose its Zookeeper lock (network glitch, being
>>> researched), and was glad to see the secondary namenode Master process
>>> took over as it should.
>>> But if my Namenode / Accumulo Master server goes down, I also lose the
>>> gc, monitor, and tracer processes as well. *Can I configure the
>>> secondary namenode in gc, tracer, and monitor files as well, or should
>>> they run on only one host at a time*?  In this case, the GC also lost
>>> its Zookeeper lock, which resulted in a cluster with no GC running at
>>> all until I caught it.
>>> Thanks in advance.

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