cheating MC/Service Guard

[Ionut Grigorescu_2]

Hello,

Does anybody know a method to "cheat" MC/Service Guard not to start some Oracle processes? I need to test a new software and that implies to shutdown the database - but MC/ServiceGuard restarts it immediately. I don't want to halt the MC/SG cluster.

Thank you in advance,
ionut

[Mark van Hassel]

Hi,

Can't you just halt the package where the database resides in, in stead of halting the entire cluster ? Or are there multiple databases in one package ?

[Stefan Farrelly]

The oracle startup commands for SG are under /etc/cmcluster/ so if you edit these files to not start whatever then when SG tries to autorestart it then it shouldnt work.

[Ionut Grigorescu_2]

I have some instructions from the software release binder:

"Cheat" the MC/SG so that it does not restart Oracle processes:
as root user on the database server, enter:
#touch /tmp/ora_smon_omc_cheating
#tail -f /tmp/ora_smon_omc_cheating &


...that seems weird for me - I simply don't understand how can I cheat the MC/SG with that..

[melvyn burnard]

this implies that your new software has some other details you are not giving.
Essentialy, your package startup script will be looking for the file that you touch, and if it finds it assumes that you want to do something other than the normal startupp, e.g. start Oracle processes but not teh database.

I suggest you read the instructions further, or contact whoever supplied you with this new software/instructions

[Ionut Grigorescu_2]

Unfortunately the guy from the supplier's helpdesk wasn't so sure :-).
But thank you anyway for your help!

Have a nice day,

ionut

[Robert Gamble]

I would rewrite the MC/SG scripts to allow for a 'maintenance mode'. This mode would check for the state of a flag. If set for maintenance, MC/SG would not monitor the critical processes, allowing for maintenace to be performed with out MC/SG restarting them or failing over to the other node(s).

Good Luck!

[raymond lei · Accepted solution]

Hi, Ionut:

Sounds like you want to shut down oracle instance without shuting down the package. Here is my two cents.

Mc/ServiceGuard monitors the processes in the pacakge by a monitor_service scrpit defined in the package control file. You need to disable this service monitor script in this case, otherwise, mc/sg will automatically start it again once the process it monitors disappears from system.

1, Edit /etc/cmcluster//.cntl
2, Find the "Start_Services" line and comment out the script definition following this line.
(The name of the scripts usually is "oracle.sh monitor" but could be another name)
3, Shut down the package: cmhaltpkg -n
4, Restart the package: cmrunpkg -n
5, Shut down oracle instance, and it should not be restarted again. If not, there must be another scripts is monitoring it. And we need detail configure file to analyze it.

Thank,

[Ionut Grigorescu_2]

Finaly I performed the test stopping the db package. But I found the script who start and monitor Oracle - it's /etc/cmcluster/sgsomomx.sh on my system. But none of the tests in the script which decide to start oracle again is based on checking a line containing ora_smon_omc_cheating .. When oracle runs there is a process ora_smon_omc running too, but the db package restarts oracle without looking at this process. However the software supplier gave me green light to test stopping the db package. Thank you all. case closed

[Bala_8]

Hi,

I don't suggest you to alter the MCSG package scripts for your testing ....

Just halt the package .....
Mount the File systems manually .....
Start your database ....
play all your testing games .....
stop your database ... restart your database ....

once u finished all your testing,
unmount the file systems ....

run MCSG package to resume your normal work ...

i hope this helps ...

-bala-

[Jehad Al-Tuwairiki]

Hi ionut

you can change your monitoring script to check for a maintenance flag, if that flag exists then MC/serviceGuard will NOT run the package on the other node.


for example change your script as follows:
--------
while true
do
# checking for maint flag
if [ -f /etc/cmcluster/pkg name/maint_flag ]
then
sleep 30

else
...
# your normal monitor script
...
...

fi
done

---------------

then when you want to test your software
just do this:
in /etc/cmcluster/pkg name/
# touch maint_flag

and take your application down, and MC/service guard will not switch the package to the other node.