Coskan’s Approach to Oracle

April 5, 2007

Questions to a new graduate (Are you ready to be a DBA)

Filed under: Diary — coskan @ 11:11 am

There are always questions in mail group threads from new graduates, like why should I choose to be DBA? or tell my about pros/cons of DBA job. I asked them the questions below and say them If you have a little hesitation on any of these questions be something else rather than DBA . Here are the questions that must be answered with Yes to give decision to be a DBA.

1- would you like to work when all of the others are on holiday ? (because of SLA’s you can do maintenance only on national holiday times mostly)

2-Would you like to wake up at 4 AM with the voice of the operator who says there is something wrong in the DB ? (no matter when you left the building for going home if you must be called then you will be called). Believe me there will always be  something wrong with the DB because database is not an install and forget system.

3- Are you calm enough to work under pressure?? This stress is not like every pressure it is the pressure comes from the distress of a man (usually your boss or his representative) who is loosing a lot money every second because of a DB fault. They can look like a monster in that crisis times.

4- Do you like to work when there are many people especially the boss or general manager (with telephone listening the boss) and his/her flatterers looking at your screen and asking when will it recover or when will the problem be solved ? For example in crisis times when you are a unix admin you will work with you primary manager, when you are a network engineer you will work with your colleagues, when you are a developer you will work with your project leader but if it is something about DB you will work in front of the ones who has great balls.

5- Are you ready not to get  of reading ?? Every oracle release has over 10 thousands of pages official documents and zillion articles and as a bad news Oracle announce new releases almost every 3 years.

6- Do you like overtimes ? Due to the fact that DB is at the center of everything (network, system, application etc) many times you will stay at office even if there is someone working on something. If there is a network work you should stay if there is a unix work you should stay if there is an update you should stay because every work can effect the DB.

7 - Would you see the database as a lover or more than a lover? DB is something like a lover or a kid. You have to show your interest every time and look after DB in 7/24 time period. Your lover or kid may thank you with a kiss or hug for your effort but DB wont :) This love and interest to DB is something like unrequited love.

8- Are you ready to stay calm over against meaningless requests of a developer who has a black box approach to DB and who believes that he is only responsible for writing code not performance ? (I want to kill the ones who wrote that is independent from DB pufffffffffff)

9- Are you careful enough?. You will play with real data and it is very easy to drop a database just like the 2 word command “drop database”. A simple where clause could change everything.

10-Are you ready to be blamed every time ? No matter what the problem is you will always be blamed first. Everyone will calumniate the DB and its Administrator because it is at the center of everything.

Again if you have hesitation to answer YES to any of these questions don’t think be a DBA . Be something else because this is the DBA’s life.

Will it worthy enough to stand all those?? I don’t know but i am happy to be an Oracle DBA.

Child Listener Problem

Filed under: Uncategorized — coskan @ 7:27 am

A while ago one of our systems faced with a child listener occurrence problem. The listener wasn’t answering the requests., when our clients were trying to reach the server through listener as a new connection.We couldn’t get the status of the listener with lsnrctl status command and nothing was written to the listener logs.

There wasn’t any problem on the database itself because local connections are accepted and database answers your requests. Also already connected users are working normally. Conclusion was “our listener hanged”

When we looked at the listener proceses we saw that there was a a child listener forked from the real listener.

#ps -ef | grep tns
oracle 22480 14188 0 18:33:57 $ORACLE_HOME/bin/tnslsnr listener_DBNAME -inherit
oracle 14188 1 0 Apr 1 $ORACLE_HOME/bin/tnslsnr listener_DBNAME -inherit

We tried to stop the listener with lsnrctl stop command but it didn’t work. (after closing the application servers)

So we killed the listener processes from OS

# kill -15 22480,14188

After the killing operation we opened the listener and everything worked well and all the connection requests were accepted. This fast action must be taken immediately and it was time to find a real solution for the problem.

Simple metalink search explained the problem and the solution. Note:340091.1 says that “This is a known problem addressed via non-published bug:4518443 (Abstract: Listener Gets Hung Up). The issue is that the TNS listener can hang under load while spawning a process” . Note has 2 solutions one is applying patch 4518443 or setting the listener parameter SUBSCRIBE_FOR_NODE_DOWN_EVENT_<listener_name> =OFF. We choose the parameter setting option and did not face with the problem again. There is something to consider about the parameter setting option for RAC systems, when you set parameter to OFF, FAN (fast application notification) will not be possible.

PS: Note says this problem can occur on any platform for releases from 10.1.0.2.0 to 10.2.0.3.0

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