Progress
Database Administration
Guide and Reference
Archiving an AI File
Backing up the AI file involves:
Scheduling Backups
Depending on your database backup schedule and needs, you might want to back up the AI files:
- Each time you perform a database backup.
Back up the AI files each time you back up the database. It should be a routine part of every backup. Also, back up the AI files on a backup media different from the database, log, and BI files. This technique provides a way to reconstruct the database by rolling forward the backup of the AI files against the previous backup of the database.
If you do choose to back up the AI files on the same media as the database, it is essential that you back up the AI files in a way that lets you restore it separately from the database, BI, and log files.
NOTE: If you back up the AI files when you perform a database backup, keep in mind that the AI files backup is used with the previous database backup.You can use the RFUTIL utility commands with online databases that have AI extents. You can perform online backups while after-imaging is enabled. The backup utility automatically marks the busy AI file as full and switches over to a new AI file.
- On a daily basis.
You should consider backing up the AI files on a daily basis if:
Before deciding to back up the AI files every day, consider that recovering the database from these small AI files is more intricate than recovering from a single, large AI file. Also, if you are using a single AI file, you must shut down the database to switch to a new AI file.
If you are using multiple AI extents, you must back up the extents regularly to ensure that the system does not run out of AI space. If you are using a single AI file, it is important to back up the AI file before you fill the disk that contains it. If you do not back it up in time, the database engine shuts down the database. For a complete description of how to recover from a full AI disk, see Recovering a Database."
Performing the Backup
You must use an operating system utility to back up the AI files regardless of whether you are using a single AI file or multiple AI files. Table 11–2 presents some of the backup options available for each operating system.
Ensure that the backup technique backs up the entire file. On many UNIX systems, certain utilities (for example,
cpio
) will back up only the first part of files over a certain size (controlled by the ULIMIT parameter). Backups of partial AI files are invalid and unusable.Marking an AI File As Empty
After you back up a file, you must mark the file as empty so that the database engine can reuse the file. To mark a file as empty, use the AIMAGE EXTENT EMPTY qualifier of the RFUTIL utility. After you mark the file as empty, the database engine overwrites the contents of the file.
Use the following command to mark the AI file as empty:
db-name
Specifies the database you are using.
extent-number
Specifies the number of the file you want to mark as empty.
extent-path
Specifies the pathname of the file you want to mark as empty.
If you do not specify an extent-number or extent-path, the database engine automatically marks the oldest full extent as empty.
NOTE: Use the RFUTIL AIMAGE EXTENT LIST or RFUTIL AIMAGE EXTENT FULL utility to determine the extent-number or extent-path.Labeling the Backup
After you back up the AI file, you must properly label the backup. Properly labeling backups helps you ensure database integrity. Follow these steps to label backups:
- Clearly label each backup. Information on the label might include the:
- Keep all daily database and AI file backups for at least two weeks. In the event that you have to roll the database forward, you can then reapply each of these daily backups to recover the lost data. If you do not keep a daily backup of the AI files and you lose the database and AI files, the most recent backup might be as much as a week old. However, if you have been doing daily backups of the AI files, you can use the most recent copy of that file to reconstruct a more recent version of the database.
- Keep backups in an area other than where the computer is located, preferably in another building. Thus, in the event of building damage, you are less likely to lose both the online and backup versions of the files.
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