• Maintain and preserve the database source code If you do not have the original database creation scripts, you can re-generate the database DDL using:
  isql -extract -output <ddl_output> <db_name>
  
• With the DDL script you should be able to re-create an empty database. Make sure that this actually works.
  

• Frequently backup and restore using GBAK. GBAK performs consistency checks and housekeeping operations that are vital to prevent database corruption.
  Restoring the database from a .gbk file builds database structures from scratch. Because it also rebuilds the indices, it is also the best way to guarantee performance.
  Also, garbage collection during backup ensures that back versions do not take up space in the restored database.
  Finally, a GBAK backup/restore cycle updates the database's On Disk Structure (ODS) when a new Interbase server version is installed.

• Do not rely on .gdb file copies as backups.
  If you must make copies of .gdb files, ensure that the server is down. In principle, it should be safe when there are no connections to the database, but then you need to be sure nonew connections can be established. That means that you need to shut down the database before copying.
  

• Regularly validate the database using GFIX Monitor the validity of the database on a regular basis. This allows you to recognize problems soon after they occur and take immediate steps.

• Regularly check the server log for errors. Sometimes, the server has crashed and recovered without anyone noticing (or warning you). Validate the database structure when a crash has occurred .

• Disable sweeping:
  gfix -housekeeping 0 <db_name>
• Validate and Repair:
  gfix -v -f <db_name>
• Mark corrupt data to skip on subsequent backup:
  gfix -m <db_name>
• Read-Only Validate to detect more validation errors:
  gfix -v -n <db_name>
• If this reports more errors, repeat the last three steps.
  

• Backup without sweeping and ignoring checksum errors.
  gbak -B -v -ig -g <db_name> <bu_name>
• Restore creating the database as new
  gbak -C -v <bu_name> <db_name>
• If the restore does not succeed, try restoring with a commit after each table:
  gbak -C -v -o <bu_name> <db_name>
  

Diagnosing and Repairing Database Corruption
Paul Beach, Sep 2000
http://www.ibphoenix.com