Kamran Agayev's Oracle Blog

Oracle Certified Master

Archive for May, 2018

The most horrific Oracle messages you might get in the production database – or – why DBAs get older

Posted by Kamran Agayev A. on 10th May 2018

If you are a production DBA of mission critical system, then you might have already seen the following critical, I would say mortal messages in your alert.log file.

  • When your database was up and running, you shutdown it and open and it fails to MOUNT the database and abort






  • The database was hanged with millions of online transactions, and aborted. You start the instance, switch to the MOUNT mode, do some maintenance tasks and try to open the database and …. wait …. wait …. wait …..











  • system01.dbf contains corrupted blocks








  • When it takes 15 hours to restore the database, you run the recover database command and get the following errors:













  • When you’ve done with restore/recover and open the database with RESETLOGS option and see the following errors:










  • When you have missing datafiles of a tablespace with 10Tb size due to hard disk corruption and don’t have a backup











  • Incomplete recovery due to missing archived log files and most probably you are going to fail using *.allow_resetlogs_corruption parameter as well













  • When your database hangs, you get a hard disk corruption and lose some datafiles, and it takes an hour and half to perform and instance recovery and you just wait for that time of period for the database to be opened:

















  • Aaaand most annoying message during the recovery









I will keep updating this post with your and my screenshots. Feel free to send me screenshot of cases where you stressed, but eventually succeeded to solve the database issue

Posted in Administration | 2 Comments »

How to pass Oracle Database 12c: RAC and Grid Infrastructure Administration exam – 1Z0-068 and become Oracle Certified Expert

Posted by Kamran Agayev A. on 3rd May 2018

In this post I will talk about my journey on how to prepare and pass the 12c RAC and Grid Administration exam.


About the exam

Check the following link to get more information about the exam from Oracle University page:



The exam consists of 3 parts:

– Oracle 12c ASM Administration
– Oracle 12c Grid Infrastructure Installation and Administration
– Oracle 12c RAC Administration


I don’t want to scare you, but the exam is hard enough. The bad thing is – you fail the entire exam if you fail one of the sections. This means that you have to be well prepared for all 3 parts. For me, I was good at ASM and RAC Administration, and was not comfortable with Grid Infrastructure Installation and Administration part which I passed barely.

You may be Oracle high availability expert and fail the exam. You might have an experience but can fail because of useless (or may be uncommon) features and topics that you didn’t practice, or didn’t read or read superficial. Because most of the questions were not checking your practical experience, but theoretical knowledge. I manage high available cluster databases for last 8 years, and it was really hard to answer some of the questions that I haven’t ever faced and I didn’t see the reason to try.
There were a lot of questions like “Choose four option, where blah blah blah ….” And you have to choose 4 options out of 7. You might know 3 correct answers, but because of that 1 wrong option you might fail.

Next, you have to achieve a minimum score for all 3 sections in order to pass the entire exam. You might complete 2 sections with 100% and fail from the one and end up failing the entire exam.


How to prepare for the exam?

You have to read the documentation and play with ASM, RAC database and Grid Infrastructure A LOT!

If you want to learn Oracle 12c Grid Infrastructure installation, check the following video tutorial:



Check the videos section in oraclevideotutorials.com to find out some clusterware related hands-on practices:



The only available book related with the exam (RAC part mostly) is the following book which is worth reading written by friends of mine Syed Jaffar, Kai Yu and Riyaj Shamsudden:

Expert Oracle RAC 12c


In my OCM preparation book, I have two chapters that can help you during the preparation:

Chapter 7 – Grid Infrastructure and ASM

Chapter 8 – Real Application Clusters.


To get free trial pdf copy of the book, go to www.ocmguide.com , or purchase it from the following link:



During the exam, I felt regret skipping reading some chapters in the documentation and viewing some of them superficial. I highly recommend to check ASM, RAC and Grid Infrastructure documentation and make sure you went through the entire documentation at least once. Here are the links to the documentations:


Real Application Clusters Administration and Deployment Guide



Clusterware Administration and Deployment Guide



Automatic Storage Management Administrator’s Guide



Setting deadlines and booking the exam

Most of you (including me) postpone the exam and don’t put deadlines for the preparation and for the exam itself. My advice – set an approximate date for the exam and make a plan for each month, week and day. Then set a date and book the exam! Yes, book it – as you have a chance to rebook if you don’t feel ready unless it’s 24 hours before the exam. Registering for the exam weeks before the exam date will push you to make your preparation completed on time.


I booked the exam for Tuesday, rebooked it to Wednesday, then to Thursday, and then to Friday :). On Wednesday I decided to reschedule it to the next Monday and in the evening I was shocked when I saw that I didn’t actually rescheduled it on Friday. It will happen tomorrow! (on Thursday) Just in a few hours! :)


I didn’t feel that I’m ready and still having few incomplete sections where I was feeling weak, even was about to cancel the exam and don’t attend, but then decided to push hard and try. And if I lose, I decided to lose like a champ :)


So I stayed awake till 3am, took a nap till 6am and made last preparations till 9am. Attended exam at 10am and was completely exhausted, overworked and sleepy.

Fortunately I passed the exam successfully and wish you the same.









This is my experience with Oracle Database 12c: RAC and Grid Infrastructure Administration exam  (1Z0-068).  Let me know if you plan to take the exam, so I guide you through it in more detail.

Good luck!

Posted in RAC issues | 1 Comment »