Infrastructure at your Service

Category Archives: Database management

David Hueber

ODA – 32GB template but got a database with 16GB SGA???

By | Database Administration & Monitoring, Database management, Hardware & Storage, Operation systems | No Comments

I got an interesting question today from a customer which created a database on ODA. He selected the template odb-04 which shows 32GB Memory but got a database with a 16GB SGA… Is it due to the PGA size, a limitation in the system, the huge pages usage which is reached or even a bug?  

 
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William Sescu

Oracle 12c – Is VKTM always your top process?

By | Database management | 2 Comments

If VKTM is always your top cpu consuming process, then this blog might be something for you. Especially in virtual environments, I have seen often the VKTM process as the top process, even if the VM was idle. So, I am burning CPU without any obvious benefit. So what is the reason for the high CPU consumption? Well … it can a combination of many things like not correctly working NTP, missing VMware Tools, but…

 
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William Sescu

Oracle 12c – How to Recover lost DataGuard Broker Configuration Files

By | Database Administration & Monitoring, Database management | No Comments

If you are using RMAN to back up your database, you are already doing the right thing. However, RMAN does not take care of everything. e.g. it is not backing up the following things, to mention just a few. Oracle Home Grid Infrastructure Home Data Guard broker files Password File SQL*Net file like ldap.ora, sqlnet.ora, tnsnames.ora and listener.ora /etc/oratab OS audit files Wallets /etc/sysctl.conf and limits.conf OLR and OCR Voting Disks ASM Metadata passwd, shadow,…

 
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William Sescu

Oracle 12c – Recreating a Controlfile in a Data Guard environment with noresetlogs

By | Database Administration & Monitoring, Database management | No Comments

Sometimes you might run into situations where the controlfile does not represent the backups and archivelogs correctly, because of a mismatch of the control_file_record_keep_time and the RMAN retention. The controlfile has non circular and a circular records. Non circular are e.g. database information, redo threads, datafiles and so on. These non circular records don’t age out, however, they can be reused, e.g. when a tablespace is dropped. The circular records are e.g. the log history,…

 
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William Sescu

Oracle 12c – How to correct the error: “RMAN-20005: target database name is ambiguous”

By | Database Administration & Monitoring, Database management | No Comments

I do have a Data Guard environment, where I have configured the RMAN DB_UNIQUE_NAME persistent setting for my primary and the standby. With the RMAN DB_UNIQUE_NAME settings I am able to run reports my Oracle Data Guard environment from any database. I could e.g. list all archivelogs for SITE1 from SITE2 or the other ways around. Or I could show all persistent settings for SITE1 from SITE2 and of course the other way around. The…

 
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William Sescu

Oracle 12c – Combining Flashback Drop and Flashback Query

By | Database Administration & Monitoring, Database management | No Comments

If you think that Flashback Drop feature just brings back your table, then this is only half of the story. It does much more than that. Besides undropping the table, it also brings back your constraints, your indexes, your trigger, your grants and the statistics as well. The ugly part is, that the flashback drop brings back some strange object names e.g. your indexes and constraints with names like “BIN$…” or alike. Maybe something you…

 
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William Sescu

Oracle 12c – Issues with the HEATMAP Segment even if the heat map feature is not used

By | Database Administration & Monitoring, Database management | No Comments

When I don’t need I feature, I don’t turn it on, or do not use it because it reduces the possibility to run into issues. Most of the times this is true, however, during the preparation for an RMAN workshop, the RMAN list failure command showed me the following dictionary issue. RMAN> list failure; using target database control file instead of recovery catalog Database Role: PRIMARY List of Database Failures ========================= Failure ID Priority Status…

 
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William Sescu

Oracle 12c – RMAN list failure does not show any failure even if there is one

By | Database Administration & Monitoring, Database management | No Comments

Relying to much on the RMAN Data Recovery Advisor is not always the best idea. In a lot of situations,  it tells you the right things, however, sometimes it tells you not the optimal things, and sometimes, RMAN list failure does not show any failure at all, even if there is one. So … let’s simulate quickly a loss of a datafile during the normal runtime of the database. The result is a clear error…

 
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William Sescu

Oracle – RMAN Backups to CIFS

By | Database Administration & Monitoring, Database management | No Comments

Not to often, but sometimes you need to offload your RMAN backups and your DataPump exports to CIFS. You might run out of space on your NFS server, or you are a Windows shop who has only CIFS shares, and then you might need to put your RMAN backups to CIFS. One very important MOS Note regarding RMAN backups to CIFS is the following Is use of CIFS Protocol for RMAN backups supported? (Doc ID…

 
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William Sescu

Oracle 12c – How to Prevent License Violation with Active Data Guard

By | Database Administration & Monitoring, Database management | No Comments

There are some articles floating around how to prevent a license violation with Active Data Guard. Some of them related to an underscore parameter “_query_on_physical” and some of them related to a startup trigger. Both of them have advantages and disadvantages. E.g. regarding the “_query_on_physical” I can’t find any MOS Note about it, and I don’t know the side effects. Oracle gives us a hard time to disable features that we don’t want to be…

 
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