Partial verification of online PROBKUP volume(s) and full verification of offline PROBKUP volumes assure they can be considered reliable. These verification routines do not result in a database restore or overwrite or update the database used to verify the backup volume in any way.
Before verifying the backup volume(s), ensure the PROBKUP completed without error.
Neither prorest -vp nor prorest -vf is a test for data corruption.
The PROREST (-vp) parameter is used to perform a
partial verification of the backup volume for bad blocks and reports whether any exist.
- The prorest utility when used with the -vp parameter instructs the prorest utility to read the backup file(s) and compute and compare the backup block cyclic redundancy checks (CRC's) with those in the block headers.
- If there is an inconsistency detected a CRC errors will be reported "CRC check failed reading backup block n"
- This is an indication that something is wrong with the backup volume(s).
- When any bad blocks are reported, it is possible to recover data from bad blocks if a redundancy factor was specified when the backup was made (-red).
- If no bad blocks are reported, then the backup should restore without issue.
Prorest "-vf" compares the contents of each backup block with the corresponding database block of the database which the backup was taken from, to see if they match.
- If the data in the database block is corrupted but it matches the data in the backup it will not generate any error. Block corruption is raised at the time the PROBKUP utility creates the backup volume, failing a complete backup and resulting in a dbdown.
- The Full Verify (-vf) should only be used immediately after a full offline backup is performed. Error 9454 is reported when inconsistency is found:
DB block in area <number> with dbkey <dbkey>, does not match backup. (9454)
Full verify failed. (3757)
- A full verify (-vf) should not be used in conjunction with online backups. The database would have changed since the backup was run the blocks recorded in the backup volume will not match those in the current database at the time the full verification check is run and will generate 9454 messages raising false alarm.
