Author: Kamran Agayev

Feed: Kamran Agayev's Oracle Blog. Few months ago, while performing storage migration I faced an interesting issue which could lead to potential downtime if I didn’t notice a hidden warning in the log file. The plan was to create a new ASM diskgroup in a normal redundancy with 2 disks from different storages and test the disk crash and confirm that there will be no data loss if one of the storages fail. After creating a diskgroup, creating a test tablespaces on it and corrupting the header of one disks, everything was ok and we decided to drop the diskgroup ... Read More

Feed: Kamran Agayev's Oracle Blog. 24 hours passed – still at work. Struggling to start up the database which was corrupted during cell storage rolling restart procedure. And I’ve never seen some Oracle error messages that I saw today. So here what is happened: ################Exadata storage cell failure during so-called “rolling cell storage restart”. Data file headers are corrupted for some files just because of rolling restart of storage cells and it can’t read the mirror file in the normal redundancy diskgroup as well!!! Both are corrupted! SR created – but there’s no reply!################ Read of datafile '+###1/###i/datafile/###_6077.1015929889' (fno 1367) ... Read More

Feed: Kamran Agayev's Oracle Blog. Today, while creating an empty database in Exadata machine where there was enough free space and memory, we got the following error: SYS@TEST> startup nomount ORA-27154: post/wait create failed ORA-27300: OS system dependent operation:semget failed with status: 28 ORA-27301: OS failure message: No space left on device ORA-27302: failure occurred at: sskgpbitsper The problem wasn’t related with the space at all, even from the error message we see “No space left on device”. From the error output, I realized “OS system dependent operation:semget“, where “sem” means “semaphore“. Having enough free memory and space, the process ... Read More

Feed: Kamran Agayev's Oracle Blog. Python is getting more popular nowadays, because it is reliable and efficient, it has great corporate sponsors, and because of it’s amazing libraries that helps you to save time during the initial development cycle. It’s much more easy to connect to an Oracle Database from Python by using cx_Oracle module. To get more information about cx_Oracle module, check the following links: https://oracle.github.io/python-cx_Oracle/  https://cx-oracle.readthedocs.io/en/latest/installation.html In this blog post, I will show how to install Python and configure the environment and connect to the database. First of all, make sure you’ve an internet connection and install Python ... Read More

Feed: Kamran Agayev's Oracle Blog. Last week we had a clusterware issue on one of the critical 3 node RAC environment. In the first node, network resource is restarted by ending up killing all sessions on that node abnormally. Oracle VIP that was running on that node failed over to the third node. The first node was up and running, but didn’t accept connections because it was trying to register the instance using LOCAL_LISTENER parameter where the oranode1-vip was specified that was not running on that node. We tried to relocate it back to the first node, but it failed ... Read More

Feed: Kamran Agayev's Oracle Blog. Last month, after long brainstorm, I decided to take my chance and accepted my participation at Indian Oracle ODev Yathra tour. Despite the fact that I’ve visited India (Hyderabad) 2 times in the past for the Sangam conferences, I wanted to discover India more and decided to take 4 cities out of 7. For the Yathra Tour I submitted 2 papers: The first one was about “8 ways to migrate your On-Premis database to Oracle Cloud” where I was talking about different ways to migrate the database based on the downtime and the migration requirements ... Read More

Feed: Kamran Agayev's Oracle Blog. Posted by Kamran Agayev A. on July 25th, 2018 Most of you already have seen that Oracle Database 18c has been already released. If you haven’t downloaded and installed it yet, let’s do it! First of all, check the following address and download the installation of Oracle Database 18c: http://www.oracle.com/technetwork/database/enterprise-edition/downloads/oracle18c-linux-180000-5022980.html If you want to download it from the host itself, you can use wget by providing username, password and the installation zip file as follows: wget –http-user=YOUR_USERNAME –http-password=YOUR_PASSWORD –no-check-certificate –output-document=LINUX.X64_180000_db_home.zip “https://download.oracle.com/otn/linux/oracle18c/180000/LINUX.X64_180000_db_home.zip” If you want to get more information on this technique, check the following metalink ... Read More

Feed: Kamran Agayev's Oracle Blog. Posted by Kamran Agayev A. on May 10th, 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 ... Read More

Feed: Kamran Agayev's Oracle Blog. 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: https://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=5001&get_params=p_exam_id:1Z0-068 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 ... Read More

Feed: Kamran Agayev's Oracle Blog. Few days ago, I was testing some ASM parameters in my 3 nodes 12.2 Clusterware environment and used ASM_PREFERRED_READ_FAILURE_GROUPS parameter to see how I can force ASM to read specific failure group. Testings were successfull but I didn’t know that this parameter is deprecated in 12.2, and beside that, I didn’t imagine that it might cause me a downtime and prevent Clusterware to start. Here’s the scenario that you can try in your test environment. First of all, I set this parameter to the failure group and then resetted it back: SQL> alter system set ASM_PREFERRED_READ_FAILURE_GROUPS=”; ... Read More