DBV utility

DBVERIFY is an external command-line utility that performs a physical data structure integrity check. It can be used on offline or online databases, as well on backup files. You use DBVERIFY primarily when you need to ensure that a backup database (or datafile) is valid before it is restored, or as a diagnostic aid when you have encountered data corruption problems.

Because DBVERIFY can be run against an offline database, integrity checks are significantly faster.

DBVERIFY checks are limited to cache-managed blocks (that is, data blocks). Because DBVERIFY is only for use with datafiles, it will not work against control files or redo logs.

Note:

If the file you are verifying is an Automatic Storage Management (ASM) file, you must supply a USERID. This is because DBVERIFY needs to connect to an Oracle instance to access ASM files.

The following is a sample verification of the file t_db1.dbf.The 
feedback parameter has been given the value 100 to display one period (.) for 
every 100 pages processed. A portion of the resulting output is also shown.


% dbv FILE=t_db1.dbf FEEDBACK=100
.
.
.
DBVERIFY - Verification starting : FILE = t_db1.dbf 

................................................................................
 

DBVERIFY - Verification complete 
 
Total Pages Examined         : 9216 
Total Pages Processed (Data) : 2044 
Total Pages Failing   (Data) : 0 
Total Pages Processed (Index): 733 
Total Pages Failing   (Index): 0 
Total Pages Empty            : 5686 
Total Pages Marked Corrupt   : 0 

Total Pages Influx           : 0 

Notes:



Pages = Blocks

Total Pages Examined = number of blocks in the file

Total Pages Processed = number of blocks that were verified (formatted 
blocks)

Total Pages Failing (Data) = number of blocks that failed the data block 
checking routine

Total Pages Failing (Index) = number of blocks that failed the index block 
checking routine

Total Pages Marked Corrupt = number of blocks for which the cache header is 
invalid, thereby making it impossible for DBVERIFY to identify the block 
type

Total Pages Influx = number of blocks that are being read and written to at 
the same time. If the database is open when DBVERIFY is run, DBVERIFY reads 
blocks multiple times to get a consistent image. But because the database is 
open, there may be blocks that are being read and written to at the same time 
(INFLUX). DBVERIFY cannot get a consistent image of pages that are in 
flux.








Using DBVERIFY to Validate a Segment




Command-Line Interface
The following example shows a sample use of the command-line interface to 
this mode of DBVERIFY.

dbv USERID=username/password SEGMENT_ID=tsn.segfile.segblock


For example, you could enter the following (assuming user hr had 
SYSDBA privileges):

dbv USERID=hr/hr SEGMENT_ID=1.2.67




Using DBVERIFY to Validate a backup file(cold backup)



dbv file=data01.dbf feedback=100