Release 10.1A: OpenEdge Data Management:
Database Administration

Archiving an AI file

Backing up the AI file involves:

Scheduling backups
Performing the backup
Protecting the backup

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 them 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 backed up are 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:

You are on a weekly full backup schedule and the AI files will grow very large during the week.
You want to perform daily backups of the AI files instead of performing incremental backups. However, it is quicker to restore your database from incremental backups than by rolling forward AI files.

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 Chapter 6, " Recovering a Database." 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. Before deciding to back up the AI files every day, consider that recovering the database from small AI files is more intricate than recovering from a single, large AI file.

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. 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. If you use ftp to transfer the AI files to a different machine, binary mode must be used. Failing to use ftp in binary will leave your AI files in an unusable state.

Protecting the backup

After you back up the AI file, make sure you:

Label the backup. Properly labeling backups helps you ensure database integrity. Include the following on the label:
Date and time of the backup.
Name of the database.
Name and type of the file.
Volume number and total number of volumes of the media, even if there is only one volume.
Initials of the person who made the backup.
Utility to use to restore the backup.
Keep all backups for at least two weeks.

In the event that you have to roll the database forward, you can then reapply each of the backups to recover the lost data. If you do not keep a 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.

In the event of building damage, you are less likely to lose both the online and backup versions of the files.

Extracting AI blocks

Extracting AI blocks from an AI extent, compacts your AI data into the smallest possible file. Extracting AI blocks can significantly shrink the size of an AI file, particularly if you have large fixed-size AI extents which are not filled to capacity. Extracting AI blocks is beneficial in cases where you are using after-imaging to replicate data, perhaps at a disaster recovery site, and you need to minimize file transfer size.

Use the AIMAGE EXTRACT qualifier of the RFUTIL utility to extract AI blocks from an extent:

rfutil db-name -C aimage extract -a ai-extent -o output-file

The output file of extracted blocks is equivalent to the source AI extent. Use the file of extracted blocks with the RFUTIL utilities to roll forward a target database. For complete syntax information see "RFUTIL AIMAGE EXTRACT qualifier" section.

Note: Extracting blocks from an AI extent is only beneficial for fixed length extents that are not filled to capacity. There will be minimal savings of disk space when extracting blocks from a variable length extent.