Clearing Unused Corrupt (Nologging) Blocks

I recently had the unfortunate experience of having to restore / recover a database that had undergone ‘nologging’ operations after the latest backup. Of course, the presence of blocks recovered through a nologging operation causes ORA-01578 errors such as ORA-01578: ORACLE data block corrupted (file # 11, block # 91658) ORA-01110: data file 11: ‘+DATADG/tollprd/datafile/toll_t01.256.849581711’ […]

Understanding UNDO

Sooner or later, every Oracle DBA will hit a problem of some sort that is related to the concept of Oracle “Undo”. The Oracle Undo performs a few very important functions in the database; these being the support of read-consistent queries and Flashback queries, supporting transactions (COMMIT and ROLLBACK), and recovering from database crashes. Along […]

Recovery of ASM Disks Using Backup Blocks on AIX

There are some simple commands (not all well documented)  to debug an ORA-15032 “not all operations performed” when a disk group won’t mount. Validate the device permissions and ownership on all nodes with a simple “ls -l /dev/rdisk*” command and correct any issues found. Run the storage check of the cluster verify utility. cluvfy comp […]

Duplicating an 11gR2 Oracle database with no connection to the target

One of the new Backup and Recovery features of Oracle 11g Release 2 (11gR2) is the ability to duplicate a database without connecting to the target database. In RMAN terminology, the “target” database is the one you wish to duplicate. In this case, the only requirement is that you provide a disk backup location where […]

Don’t Fall Into This RMAN Trap

Have you found that daily full database backups are becoming impractical for your growing databases?  Incremental backups are no longer the exception in some shops.  But with the increased complexity comes a greater responsibility for thoroughly planning and testing your backup solution.  Testing a more complicated backup solution makes for a more complicated validation procedure.  […]