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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 – 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 12cR2 – RMAN cold backup with TAG’s

By | Database Administration & Monitoring, Database management | One Comment

I am planning to backup my 12R2 container database, because a huge application change is coming up, and I want to be sure that I have a good RMAN backup beforehand. For that particular DB, I want to do it with a cold backup in combination with RMAN tags. Unfortunately I don’t have any backups at the moment, so I start with a full backup with the TAG ‘DBI_BACKUP’ to be 100% that I restore…

 
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William Sescu

Oracle 12cR2 – DataGuard and Backups to NFS

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

From the RMAN point of view, you have generally two possibilities to store your backups, on Disk or on Tape. In case of a single instance, it doesn’t really matter from the accessible or inaccessible point of view. However, in a DataGuard environment it makes a huge difference. Per default, backups to Tape are always accessible and backups to disk always inaccessible. But what do you do in case you backup to NFS, and you…

 
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William Sescu

Oracle 12c – Finding the DBID – The last resort

By | Database Administration & Monitoring | No Comments

The DBID is a very important part for Oracle databases. It is an internal, uniquely generated number that differentiates databases. Oracle creates this number automatically as soon as you create the database. During normal operation, it is quite easy to find your DBID. Whenever you start your RMAN session, it displays the DBID. oracle@oel001:/home/oracle/ [OCM121] rman target / Recovery Manager: Release 12.1.0.2.0 – Production on Mon Nov 28 10:32:47 2016 Copyright (c) 1982, 2014, Oracle…

 
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William Sescu

Oracle 12c – DB_UNKNOWN in ASM

By | Database Administration & Monitoring | No Comments

Have you ever noticed a DB_UNKNOWN directory in your ASM structure? It usually happens in combination with spfile creation in ASM, or with RMAN spfile restores to ASM. The correct location is +DATA/<SID>/PARAMETERFILE/SPFILE.<#>.<#>, and an ASM alias from +DATA/<SID>/ pointing to it. But sometimes, the spfile ends up in +DATA/DB_UNKNOWN/PARAMETERFILE/SPFILE.<#>.<#> Technically no issue. The spfile in the DB_UNKNOWN directory is perfectly ok and can be used. However, you might need to adjust your init<SID>.ora in…

 
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