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From "Terry P." <texpi...@gmail.com>
Subject Re: Accumulo Standby Master question
Date Wed, 13 Nov 2013 22:12:04 GMT
Revisiting this, looks like I found even when I have my secondary namenode
hostname in the gc file on the master and secondary namenode (my standby
master), the gc process would not start on any node but the master.

Looking at the config.sh script on lines 102-104:

if [ -f "$ACCUMULO_HOME/conf/gc" ]; then
    GC=`grep -v '^#' "$ACCUMULO_HOME/conf/gc" | head -1`
fi

That only puts the first node found in the GC variable, similar to what is
done with MASTER.

Then in start-here.sh, whereas the masters file is checked to see if the
current host is in the masters file (starting at line 38):

for host in $HOSTS
do
    *if grep -q "^${host}\$" $ACCUMULO_HOME/conf/masters*
    then
       ${bin}/accumulo org.apache.accumulo.server.master.state.SetGoalState
NORMAL
       ${bin}/start-server.sh $host master
       break
    fi
done

*For GC, only the ${GC} variable is checked (starting on line 48), and
start of the gc is only attempted on the one host in the GC variable*:

for host in $HOSTS
do
    *if [ ${host} = ${GC} ]*
    then
        ${bin}/start-server.sh *$GC* gc "garbage collector"
        break
    fi
done

*I've modified my start-here.sh script's GC section to*:

for host in $HOSTS
do
    *if grep -q "^${host}\$" $ACCUMULO_HOME/conf/gc*
    then
        ${bin}/start-server.sh *${host}* gc "garbage collector"
        break
    fi
done

And that did the trick.  I didn't see any changes needed in the
stop-here.sh script, as it already iterates over all possible processes to
stop them if they are found.

Can anyone think of anything I might have missed?

I searched for any JIRAs on this but did not find any.

I tried to download the 1.5.0 binaries, but download link doesn't work for
me (has happened before with my work's overly restrictive internet gateway)
-- but FYI I asked my brother to download it, and the "mirrors" link under
GENERIC BINARIES didn't work for his as well.

If I can get my hands on the 1.5.0 binaries, I'll check to see if this is
already OBE in 1.5.0 today else it will have to wait until tonight.



On Wed, Nov 6, 2013 at 12:12 PM, Terry P. <texpilot@gmail.com> wrote:

> Ahh thanks Billie, I'll stick with just one monitor then.  Thanks!
>
>
> On Wed, Nov 6, 2013 at 10:32 AM, Billie Rinaldi <billie.rinaldi@gmail.com>wrote:
>
>> On Tue, Nov 5, 2013 at 12:51 PM, Josh Elser <josh.elser@gmail.com> 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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