The following steps briefly identify the PROBKUP process:
1. Establish a database latch (online only).
2. Do a pseudo checkpoint (online only).
3. Switch AI files (if applicable).
4. Back up the primary recovery area (online only).
5. Release the database latch (online only).
6. Back up the database.
The database is backed up from the high-water marks downward. Free blocks are compressed to save space. Online backups represent the database at the time the backup started. All transactions started after the backup begins are not in the backup, and will not be in the database when a restore and transaction rollback occurs.
The reason for the pseudo checkpoint in an online backup is to synchronize memory with disk prior to backing up the database. This synchronization is critical because then the PROBKUP utility can back up all of the data that is in the database and in memory at that moment. Other utilities can only back up the information on disk, thus missing all of the "in memory" information.
