HP 3000 Manuals HP 3000 Manuals
Consistent Backups Even though database files generally constitute the largest part of any backup, TurboSTORE/iX 7x24 True-Online Backup also backs up system and non-database files. Since TurboSTORE allows changes to files during a backup, it establishes a close tie to the file system to ensure physical and logical consistency. Physical Consistency Physical consistency is ensured by providing a snapshot of the fileset at a specific point in time, specifically, at the sync point. This is adequate for files that are not "related" to other files, and have no dependencies on changes to other files. This includes system files, some flat files and any other files not associated with a database. For KSAM XL files and files enabled for transaction management, TurboSTORE guarantees that no partial transactions are included in the copy of the file stored on the tape. This ensures that a consistent copy of the file is stored. If Native Mode Message files are open during the sync point, TurboSTORE follows the necessary steps to successfully imitate closing the file to ensure data integrity, physical consistency, and recoverability. User-mapped files are managed the same way they were with as TurboSTORE/iX II with Online Backup. Whenever changes are made to a user-mapped file being stored by a 7x24 true-online backup, the entire file is copied to TurboSTORE's log files. However, if a user-mapped file is left open for write access across the sync point, then TurboSTORE captures the last known state of the file, which would either be at the last FOPEN, FCLOSE, or FCONTROL 6. If TurboSTORE does not capture any of these events, the file is stored in whatever state it was in when TurboSTORE opened the file, which may be inconsistent. A warning message is printed for all user-mapped files open across the sync point.
NOTE Compatibility mode (CM) files, namely Circular (CIR) files, and Relative I/O (RIO) files have internal buffer structures that cannot be logged by TurboSTORE. If these files are open for write access during the sync point, TurboSTORE captures their last known state, which is either since the last FCLOSE or the last FCONTROL 6. A warning is issued for all CM files that were open across the sync point.
Logical Consistency In addition to physical consistency, TurboSTORE/iX 7x24 True-Online Backup also guarantees logical consistency for databases. This is done by setting the sync point to occur when all open transactions against the databases have completed. No new transactions can start until the open transactions are complete, which is called quiescing the database. Although any type of database can be stored by TurboSTORE, only TurboIMAGE and ALLBASE/SQL databases are automatically quiesced using special database intrinsics.
NOTE Quiescing an ALLBASE/SQL database and storing the ALLBASE/SQL database by TurboSTORE/iX 7x24 True-Online Backup when the DBEnvironment is in normal use, has the same effect as using the STOREONLINE command of SQLUtil. For a 7x24 true-online backup of ALLBASE/SQL to be of use for rollforward recovery, use the same procedures you would use when doing the STOREONLINE commands.
If you need to synchronize any other file types (e.g., CM file types such as CIR files and RIO files) and/or any third-party databases that are not automatically synchronized, you can manually quiesce these before beginning the backup, or during the backup by specifying the ASK parameter with the ONLINE option. ASK makes TurboSTORE wait at the sync point while you finish these operations. Refer to "Prompting During Backup (ASK)" later in this chapter for a description of the ASK parameter. Once all files and databases are quiesced, TurboSTORE establishes the logically consistent synchronization point. It then unquiesces all TurboIMAGE and ALLBASE/SQL databases.
NOTE Only open databases being stored by a TurboSTORE/iX 7x24 True-Online Backup are quiesced. If a database is being stored, but is not opened for write access, it is not quiesced.