Posted by Kamran Agayev A. on June 13th, 2014
Just came across a wonderful blog where you can find dozens of different Oracle related video tutorials
Posted by Kamran Agayev A. on June 13th, 2014
Just came across a wonderful blog where you can find dozens of different Oracle related video tutorials
Posted by Kamran Agayev A. on May 29th, 2014
As you’ve already known, you should use odd number of disks for voting disk. A node must be able to strictly access more than half of the voting disks at any time. Let me show you how it works. I have installed and configured two node 11gR3 RAC on VirtualBox and use the following case to show how it works:
- Create a diskgroup with 3 failure groups and 3 different disks
- Move voting disk to the new diskgroup. Shutdown the second node and deattach one of the disks. In this case, cluster should start as it can access more than half of the voting disks (2 from 3)
- Start the second node. The cluster should be up. Shut the second node again and deattach the second voting disk. And start it. The cluster will not start. Check the ocssd.log file
- Shut down all node, attach the previous disks and start it again. Cluster will be up
Here’re the detailed steps:
- Create a diskgroup :
- Mount the diskgroup at the second node:
SQL> ALTER DISKGROUP vdisk MOUNT;
- Replace voting disk, move it to the new diskgroup and query the voting disk:
- Shutdown the second instance and reattach one of the disks of VDISK diskgroup :
- Star the second node, query the Voting disk and check if the clusterware is up:
- Shutdown the second node again, remove the second disk from the Voting diskgroup and start the node:
- Check the log file at $GRID_HOME/log/node2/cssd/ocssd.log :
2014-05-29 01:51:23.055: [ CSSD]clssnmvVerifyCommittedConfigVFs: Insufficient voting files found, found 1 of 3 configured, needed 2 voting files
2014-05-29 01:51:23.055: [ CSSD](:CSSNM00020:)clssnmvVerifyCommittedConfigVFs: voting file 0, id 279c162c-1b964f88-bfb1d622-aecc9e4e not found
2014-05-29 01:51:23.055: [ CSSD](:CSSNM00020:)clssnmvVerifyCommittedConfigVFs: voting file 1, id 7e282f3f-5e514f42-bfb79396-c69fda76 not found
2014-05-29 01:51:23.055: [ CSSD](:CSSNM00021:)clssnmCompleteVFDiscovery: Found 1 voting files, but 2 are required. Terminating due to insufficient configured voting files
- As you see, cluster is down. Now, shutdown both nodes, add disks to the second node and check the status of the clusterware:
Posted by Kamran Agayev A. on May 27th, 2014
It took me some time to investigate why CRSCTL REPLACE VOTEDISK command is not working.
[oracle@node1 ~]$ crsctl replace votedisk VDISK
CRS-4264: The operation could not be validated
CRS-4000: Command Replace failed, or completed with errors.
When you get an error during VOTEDISK replacement, make sure you check the following items:
- Make sure the disk group you’re moving the voting disk is mounted on all nodes.
- Make sure the compatibility parameter is set to the version of Grid software you’re using. You can change it using the following command:
alter diskgroup VDISK set attribute ‘compatible.asm’=’11.2′;
Query V$ASM_DISKGROUP view to make sure it’s the same with the rest disk groups and with the version of the Grid Software:
select group_number, name, compatibility, database_compatibility from v$asm_diskgroup;
- Check alert.log file of an ASM instance, any available trace file of the ASM instance. Check /var/log/messages file and trace the replace command usint strace file. See if you can catch any error from the log file:
[grid@node5 ~]strace crsctl replace votedisk VDISK
- Make sure you’ve an odd number of votedisk
- Make sure there’s enough space in the diskgroup
- Make sure disk permissions is correct
- Make sure you’re running the command using Grid Software owner
Today, all above mentioned checks are failed . In my case, the problem was using incorrect “crsctl” command. After upgrading the RAC environment from 11.2.0 to 11.2.3 I was still using old crsctl (by accident, forgot to set environment variables correctly). But no need to worries, it was a test database.
Let me know if you have any additional check to investigate voting disk replace failure
Posted by Kamran Agayev A. on March 3rd, 2014
One of the reason of why cluster won’t start is DIAGNOSTIC_DEST folder is missing. Here it is what I got today in of the nodes of the RAC environment:
db-bash: crs_stat -t
HA Resource Target State
———– —— —–
error connecting to CRSD at [(ADDRESS=(PROTOCOL=IPC)(KEY=ora_crsqs))] clsccon 184
While checking alert log file of the clusterware ($GRID_HOME/log/node1/alertnode1.log
[/home/oracle/11.2.0/grid_1124/bin/oraagent.bin(4745)]CRS-5011:Check of resource “+ASM” failed: details at “(:CLSN00006:)” in “/home/oracle/11.2.0/grid_1124/log/node01/agent/ohasd/oraagent_oracle/oraagent_oracle.log”
ASM instance failed to start. I connected to ASM instance and tried to start it manually:
SQL*Plus: Release 184.108.40.206.0 Production on Mon Mar 3 10:32:24 2014
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to an idle instance.
ORA-48108: invalid value given for the diagnostic_dest init.ora parameter
ORA-48140: the specified ADR Base directory does not exist [/home/oracle/11.2.0/dbhome]
ORA-48187: specified directory does not exist
HPUX-ia64 Error: 2: No such file or directory
Additional information: 1
ADR Base Directory is missing. After creating it, I successfully started the CRS and got the happiest message :
db-bash-$ crsctl check crs
CRS-4638: Oracle High Availability Services is online
CRS-4537: Cluster Ready Services is online
CRS-4529: Cluster Synchronization Services is online
CRS-4533: Event Manager is online
Posted by Kamran Agayev A. on March 2nd, 2014
After migrating 10gR2 single instance to 11gR2 RAC db, the next step should be configuring Enterprise Manager (if you don’t use centralized Grid Control)
It can be done by a simple command. But as usual (at least for me) it didn’t go smooth and I got some errors . In this article I will show you solutions for some of them.
The command should be run is as follows:
emca -config dbcontrol db -repos create –cluster
It will ask you to provide the following information:
db-bash-$ emca -config dbcontrol db -repos create -cluster
STARTED EMCA at Mar 2, 2014 3:03:19 PM
EM Configuration Assistant, Version 220.127.116.11.0 Production
Copyright (c) 2003, 2011, Oracle. All rights reserved.
Enter the following information:
Database unique name:
Listener port number:
Password for SYS user:
Password for DBSNMP user:
Password for SYSMAN user:
Email address for notifications (optional):
Outgoing Mail (SMTP) server for notifications (optional):
ASM ORACLE_HOME :
ASM port :
ASM username [ ASMSNMP ]:
ASM user password:
- Get Database unique name from db_unique_name parameter from the database
SQL> show parameter db_unique_name
- To provide a service name, get the SCAN listener name from the host (ps –ef | grep tns), get the status of SCAN listener by running lsnrctl status LISTENER_SCAN1 command from $GRID_HOME and get the service name from the output
Service “RACDB.MYCOMP.COM” has 3 instance(s).
Instance “RACDB1″, status READY, has 1 handler(s) for this service…
Instance “RACDB2″, status READY, has 1 handler(s) for this service…
Instance “RACDB3″, status READY, has 1 handler(s) for this service…
- Make sure all password files at all nodes – orapwNODE1[2-3] – are same. If not, create a password file at each node and provide the same password
- As a Cluster Name, provide the name of the cluster. To get the cluster name, use the following command:
- Make sure you’ve ASMSNMP user created at ASM instance and SYSDBA privilege is granted. Do it in the first node, then copy ora+ASM1 to the different nodes under $GRID_HOME/dbs/+ASM[1-2]
Hope above mentioned notes will help you to create EM db control successfully for your RAC environment.
To get more information from metalink, use the following MOS:
How to manage DB Control 11.x for RAC Database with emca (Doc ID 578011.1)
Posted by Kamran Agayev A. on January 17th, 2014
While playing with OCR recovery, suddenly I realized that V$ASM_DISKGROUP view gets information from the headers of the ASM disk files that are specified at *.ASM_DISKSTRING parameter. Here’s the description of V$ASM_DISKGROUP view from documentation:
V$ASM_DISKGROUP displays one row for every ASM disk group discovered by the ASM instance on the node.
I got explain plan of V$ASM_DISKGROUP to know which X$ table stand behind it and got – X$KFGRP
SQL> set autotrace on
SQL> select count(1) from v$asm_diskgroup;
SQL> select name_kfgrp from x$kfgrp;
SQL> select GRPNUM_KFDSK, NUMBER_KFDSK, STATE_KFDSK, ASMNAME_KFDSK, PATH_KFDSK from x$KFDSK;
Then I queried ASM_DISKGROUPS parameter :
SQL> show parameter disk
NAME TYPE VALUE
———————————— ———– ——————————
asm_diskgroups string OCR, DATA, FLASH
asm_diskstring string /dev/oracleasm/disks
No I will create a new tablespace under FLASH diskgroup, create a new table, change owner of the disk of FLASH diskgroup and make it #*disappear* from V$ASM_DISKGROUP view, and then return everything back
SQL> create tablespace new_tbs datafile ‘+FLASH’;
SQL> create table new_table (id number) tablespace new_tbs;
SQL> insert into new_table values(1);
1 row created.
SQL> select * from new_table;
I create a parameter file from spfile, change ASM_DISKGROUPS parameter to OCR,DATA (remove FLASH) and mount the ASM instance again using a parameter file with
So DISK6 is member and as the disk is discovered by ASM instance, FLASH diskgroup is dismounted, but still there.
Let’s change the owner of the disk and check it again. But before checking the owner, let’s read it’s header by KFED:
[root@node1 disks]# kfed read DISK6
Query X$KFGRP view:
Switch to the database and check if you can query the table:
SQL> select * from new_table;
select * from new_table
ERROR at line 1:
ORA-01157: cannot identify/lock data file 8 – see DBWR trace file
ORA-01110: data file 8: ‘+FLASH/rac/datafile/new_tbs.257.837080939′
Now shutdown the ASM instance, return the owner back and check V$ASM_DISKGROUP again:
FLASH diskgroup appeared, however it’s not specified at ASM_DISKGROUPS parameter. Now mount the diskgroup and query the table again:
SQL> alter diskgroup flash mount;
SQL> select * from new_table;
This means that if you want to move the ASM instance to another host, it’s enough to specify ASM_DISKSTRING parameter, V$ASM_DISKGROUP will discover all diskgroups
Posted by Kamran Agayev A. on September 22nd, 2013
It’s 3.50 AM at San Francisco and I’m finalizing a new video tutorial that I have been creating for the users who will attend RAC Attack at Oracle Openworld 2013 (Ninja Operation). Tomorrow is the first day of OOW13 and I’m very happy that I was able to finish it in time. The first minutes of this tutorial was created in the plane when I was flying to SFO this week
For the step by step instruction, I’ve used the following article
You can download the video from this link:
Hope you’ll enjoy the video!
Posted by Kamran Agayev A. on September 19th, 2013
I’m proud to announce that I’m one of the 10 RAC Attack Ninjas this year! If you’re attending OOW13, don’t forget to come and say “hi” to Ninjas. We’ll be at OTN Lounge in the lobby of Moscone South on 24th and 25th September between 10am-2pm
Using documentation created by Ninjas, you’ll be able to install and run Oracle 12c RAC on your laptop!
For the step by step introduction, check the following link:
To get more information about RacAttack event, check the following link:
You can check our facebook page:
And don’t forget to use #RACAttack hashtag.
I’m working on “Step by Step Installing Oracle 12c RAC Video tutorial” and hope it will be ready for the RACAttack event. If you don’t have time to install it during OOW days, come and watch the video tutorial and learn how to install Oracle 12c RAC
See you all soon!
Posted by Kamran Agayev A. on September 13th, 2013
My book is out!
I would like to announce to all my fellow DBA friends that my book is published and is available at Amazon.
It took me more than one year to write it. 3 years ago I got an email from Rampant Techpress where they asked me if I can write a book about RMAN Backup and Recovery. I wasn’t ready at that time, but decided to accept that challenge and agreed. The first man came in my mind to help me at that time was my friend Aman Sharma. He also agreed and we started the journey together.
After writing the first chapter I realized that we really need to have technical reviewers, so I asked Syed Sabdar and Hemant K. Chitale if they can help us. Fortunately they agreed. I would like to thank them both as they did a great job and made a lot of corrections
All chapters are based on practical scenarios and deep research and I hope it will help you to understand RMAN in depth, to create your own RMAN backup strategy and to recover from any type of failures you can face in your production database. There’re a lot of scenarios under each chapter with an explanation and step by step guide to help you to reproduce them on your test environment
Posted by Kamran Agayev A. on August 16th, 2013
This is it! Finally I’ve successfully passed OCM exam. It was almost more than 1 year that I’ve been preparing for this.
It’s almost impossible to find additional information about the exam online, so I decided to make my own preparation plan as I’ve done it for OCP exams before. And I would like to share my preparation tips with you and hope it will motivate you to start thinking about OCM.
“It is literally true that you can succeed best and quickest by helping others to succeed.” - Napoleon Hill
Please note that this document has already been checked and approved by Oracle Certification Team.
- In parallel to working as a production DBA at a leading mobile operator company in Azerbaijan (Azercell Telecom LLC), I decided to make a preparation plan for 9 months. I printed exam topics from this link and put it on my desktop. I planned to spend a month on each section for preparation (there are total 8 sections)
- For each section and topic I went through the documentation, checked blog posts, studied metalink notes and created my own practices. I installed VirtualBox on my laptop and used it for all type of practices including RAC and Data Guard. I created different practices for each topic of each session, assigned a time frame for each practice and tried to solve them in a very limited time. I tried to not use GUI in all kind of scenarios. I was able to install Oracle Software and create a database both in silent mode using almost all parameters in a few minutes (with closed eyes ) . I learned all commands by heart; I was able to create a Data Guard using command line without looking to the documentation. I created RAC for several times, added and deleted nodes, went through all configuration and management issues. If you’re preparing for OCM exam, you have to forget GUI at all!
EM is a very important tool which has to be used on your production system and which helps you to administer all your databases from one window. You have to know every single link and page on EM, however you shouldn’t rely only on EM, because there may be some tasks which should be performed without EM. And don’t forget to master EM, as the second Section is all about Grid Control
- You have to be prepared for any type of corruption at any time during the exam. You have to test all kind of failure scenarios and recover from any type of error. If you are not able to recover your database during the exam, you will have to return home earlier. I created all kind of corruption and failure scenarios, and prepared and tested all “How to recover if …” cases.
- Each time I studied everything related to any topic and solved all practices, I removed that line from the paper. My aim was to have a paper with everything removed out like this :)
- I sensed that I would have to fight against the time during the exam, so I decided to improve my typing speed. For the last 7 years I’ve been typing without looking at the keyboard, but it wasn’t enough for me. I decided to improve my typing speed and accuracy, thus registered at www.typeracer.com and competed every day. As a result my typing accuracy improved further.
- After 8 months I finished my research almost for every section and topic of an OCM exam. For the 3 weeks of the last month I performed all practices that I had made for myself (all practices per week!). For the last week I did all practices per DAY! Every time it took me a few hours to finish all tasks. In the last week I realized that my fingers type faster than my brain process It was very hard to devote some hours per day for all practices, so I was preparing over the lunch breaks, after work, and mostly on weekends.
Finally, registration day arrived. Actually, I had planned that date before the preparation and started the registration 2 months before the exam. When you register for the exam try to check the nearest country, book the nearest hotel to the exam center, get a document to have a VISA from the embassy and book flight tickets. Don’t forget to contact OCM exam center 1-2 weeks before an exam to make sure that the exam will proceed and make sure you’ve received a confirmation letter from Oracle.
Before taking an OCM exam, you have to earn OCP certification and take 2 Oracle University (OU) courses. You can check this link for more information. If you haven’t taken the required courses before, it would be better to take the topic that you don’t feel at ease. After taking the required courses, you should submit them at Course Submission Form using course Enrollment ID
Also don’t forget to print addresses of the hotel and the exam center. On the first day I could not explain where to go unless I showed the printed address to the taxi driver. Don’t forget to take your ID to the exam center. In my case, I forgot it, came back to the hotel 1 hour before the exam started, was stuck in a traffic jam and finally got to the exam center 10 minutes ago
Although I had not a chance to relax (slept only 3 hours before the exam), but I would strongly advise you to have a rest a day before the exam.
About the exam
Exam starts at 9.00 and finishes at 18.00. You should arrive 1 hour before the exam. Don’t forget to bring your Oracle Testing ID with you
You will not get any bug during the exam. The proctor is responsible for the discipline, provides information in the beginning of each section and doesn’t answer to any technical question. You can use nonsearchable documentation.
You need to find syntax of any command in a second, you have to know which book, which chapter and which section you need to look for specific topic or question. During preparation days, don’t use documentation search and google AT ALL! In some cases, you don’t have the second chance to correct the mistake you’ve made. You don’t have any chance to learn something during the exam. If you don’t know any topic or haven’t done it or practiced it before, or even don’t know where to find the information in the documentation just go to the next question. I’m sure you’ve already done the same at OCP exam
As I’ve signed NDA, I can’t provide more information about the exam. In a nutshell, you’ll struggle against the time during the whole exam. I want to repeat again – If you come across a question that you haven’t prepared for and seen any time before, that can be a big problem. Theoretical knowledge is not enough; you have to have a practical experience.
In order to avoid feeling nervous during the exam, you are supposed to have gone through the same experience during your DBA life. If you’ve faced such critical issues and solved them in time, then the exam will be less excited.
In conclusion …
It doesn’t matter how experienced you are, it is still very challenging to use only command line interface to perform any requirement, to solve data corruption and recover the database from any data loss, create and manage RAC and Data Guard in a very limited timeline, tune the database and perform different kind of administrative tasks one by one without any mistake.
I hope my preparation method will help you start the preparation for the OCM exam. If you have any question, please do not hesitate to post your comment.
First and foremost I would like to thank The Alimighty God. He has given me the power to believe in my passion and pursue my dreams. I could never have done this without the faith I have. Sincere thanks to my family, especially to my father who motivated me every day. I would also like to thank to my collegues, my friends and all my students for supporting me. Thank you for being genuinely happy for my success and good fortune, as if it were your own
And last but not least, I would like to share some motivation quotes which can help you to be motivated during the preparation and also in your entire life