Executing dbv and Interpreting the Output

September 9,  2003
Don Burleson
 

dbv file=/usr/oracle/asg920xr/datafiles/ASG920xrsys.dbf
blocksize=8192

Once executed, dbv provides the following output for each file it verifies:

Total Pages Examined         : 52480
Total Pages Processed (Data) : 36617
Total Pages Failing (Data)   : 0
Total Pages Processed (Index): 4430
Total Pages Failing (Index)  : 0
Total Pages Processed (Other): 1664
Total Pages Processed (Seg)  : 0
Total Pages Failing (Seg)    : 0
Total Pages Empty            : 9769
Total Pages Marked Corrupt   : 0
Total Pages Influx           : 0

The output from dbv is not intuitive at first glance. Below are the definitions for each data item.

• Total Pages Examined – The number of blocks inspected by dbv. If the entire file was scanned, this value will match the BLOCKS column for the file in v$datafile.

• Total Pages Processed (Data) –The number of blocks inspected by dbv that contained table data.

• Total Pages Failing (Data) – The number of table blocks that have corruption.

• Total Pages Processed (Index) –The number of blocks inspected by dbv that contained index data.

• Total Pages Failing (Index) – The number of index blocks that are corrupted.

• Total Pages Processed (Seg) – This output is new to 9i and allows the command to specify a segment that spans multiple files.

• Total Pages Failing (Seg) – The number of segment data blocks that are corrupted.

• Total Pages Empty – Number of unused blocks discovered in the file.

• Total Pages Marked Corrupt – This is the most important one. It shows the number of corrupt blocks discovered during the scan.

• Total Pages Influx – The number of pages that were re-read due to the page being in use. This should only occur when executing dbv against hot datafiles and should never occur when running dbv against cold backup files.

Deep inside the operating system executables there are many utilities at the fingertips of Oracle professionals, but until now there has been no advice on how to use these utilities. From tnsping.exe to dbv.exe to wrap.exe, Dave Moore describes each utility and has working examples in the online code depot. Your time savings from a single script is worth the price of this great book.

For more details on Oracle utilities, see the book "Advanced Oracle Utilities" by Bert Scalzo, Donald K. Burleson, and Steve Callan. You can buy it direct from the publisher for 30% off directly from Rampant TechPress.

Regards,

    Don Burleson
    www.dba-oracle.com
    www.remote-dba.net