RE: RMAN backup validate

Identify the corruption extension using RMAN/DBV/ANALYZE etc (Doc ID 836658.1)

RMAN Vs DBVerify - Datafile Intra Block Corruption

It has been a dilemma of what tool to use when identifying intra block corruptions. Here are some comparisons between RMAN and DBV:

• When the logical option is used by RMAN, it does exactly the same checks as DBV does for intra block corruption.
• RMAN can be run with PARALLELISM using multiple channels making it faster than DBV which cannot be run in parallel in a single command. See Note 472231.1 <https://support.oracle.com/epmos/faces/DocumentDisplay?parent=DOCUMENT&sourceId=836658.1&id=472231.1> for examples.
• DBV checks for empty blocks. In 10g RMAN may not check blocks in free extents when Locally Managed Tablespaces are used. In 11g RMAN checks for both free and used extents.
• Both DBV and RMAN (11g) can check for a range of blocks. RMAN: VALIDATE DATAFILE 1 BLOCK 10 to 100;. DBV: start=10 end=100
• RMAN keeps corruption information in the control file (v$database_block_corruption, v$backup_corruption). DBV does not.
• RMAN may not report the corruption details like what is exactly corrupted in a block reported as a LOGICAL corrupted block. DBV reports the corruption details in the screen or in a log file.
• DBV can scan blocks with a higher SCN than a given SCN.
• DBV does not need a connection to the database.

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Yong Huang Sent: Monday, March 16, 2015 10:05 AM
To: mgogala_at_yahoo.com
Cc: Oracle-l Digest Users
Subject: Re: RMAN backup validate  

> The "check logical" part is what used to be known as "dbv".  

I'm curious about this comparison. Documentaion calls dbv "an external command-line utility that performs a physical data structure integrity check". If the words "physical" and "logical" are used consistently, RMAN check physical (which is default) would be equal to dbv, and check logical adds something extra. But of course "physical" and "logical" could have slightly different meanings in different tools.  

Yong Huang  

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