MMM Switching a Sluggish MySQL Server to Offline

[dze]

I had a situation where my master MySQL server became sluggish to the
point it was not usable. The server was responsive but it would take
30 seconds to respond to a request. MMM never switched the server to
AWAITING_RECOVERY or HARD_OFFLINE, which would have been my desired
behavior. The backup master was in a good state but was never
utilized by MMM.

What caused the sluggish behavior was that MySQL Enterprise Monitor
Agent had used all the RAM on the machine and virtual memory was being
thrashed. This left the server working but in a severely crippled
state.

Would anyone have suggestions on how to setup MMM to detect this
sluggish MySQL server state.

[Manuel Arostegui Ramirez]

2011/5/19 dze <do...@enav.us>

Hi, 

When I had servers swapping or about to die due to OOM this worked for me:

 

<check ping>

check_period 1

trap_period 2

   timeout 1

</check>

<check rep_threads>

        check_period 120 

        trap_period 180 

        timeout 1 

</check>

<check rep_backlog>

        check_period 120 

        trap_period 200

        timeout 1

</check>

<check mysql>

        check_period 1 

        trap_period 5 

        timeout 1

</check>

[Doron Enav]

I tried adding this block of configurations to my mmm_mon.conf file.

I still get inconsistent behavior by the monitor when the MySQL server
is OOM. While testing once the master server switched after 2 minutes
and on the following try it took 20 minutes.

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[Manuel]

El vie, 20-05-2011 a las 14:55 -0400, Doron Enav escribió:
> I tried adding this block of configurations to my mmm_mon.conf file.
>
> I still get inconsistent behavior by the monitor when the MySQL server
> is OOM. While testing once the master server switched after 2 minutes
> and on the following try it took 20 minutes.

If I get an OOM, whilst recovering the machine and all that I always
make sure to restart mmm_agentd as may have affected its performance.

Manuel

--
Manuel Arostegui Ramirez.

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