Kbase P19506: Incremental backups: Can they include full backups?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
05/11/2009 |
|
Status: Verified
GOAL:
Incremental backups: Can they include full backups?
GOAL:
Using the overlap factor (-io).
FACT(s) (Environment):
All Supported Operating Systems
Progress/OpenEdge Product Family
FIX:
An incremental backup saves the data that has changed since the last full or incremental backup was performed. This is useful because it often takes less time and media to back up the database this way.
In a PROGRESS database, the master block and every database block contains a backup counter. The counter in the master block is incremented each time the database is backed up with an on-line, an off-line, full, or incremental backup.
When you use incremental backups they must be applied in chronological order to a restored copy of a full backup of the db. Once the database has been fully backed up again, the counter in the masterblock is reset and the incremental backups are counted from that point.
However, if you use the -io option, this allows you to decrease the number of incremental backups which must be applied to your restored database. For example, if -io = 5, then you only need to apply every 5th incremental backup to your restored database, as these include all the changes that were made to the database in the preceeding four increments. -io is cumulative.
Using overlapping factor allows you to treat full backups of your database as if they were incremented ones. This is useful if your full backup becomes unavailable, as in the case when the media for a full backup becomes damaged or inaccessible. Using the overlapping factor, however, can mean that the incrementals will include ALL of the full backup preceeding it; after all, creating a full backup means that the entire database has "changed" (because each block has been read and written in the process). Consequently, it is possible to restore an earlier database and apply incrementals even if a full backup occurs in the interim.
To use incremental backups with the overlapping factor, use the following syntax:
probkup db-name devicename -io i
For restores, you use the following syntax:
prorest dbname incrementalname
If you are storing an incremental backup, using overlapping factor, AND you are including a full backup of the database as one of your incrementals, you will see the following message:
This is an incremental backup of <fulldbname>. This backup was taken at <time/datestamp>. It is based on the full backup of <last full backup>. It will require x blocks to restore.
WARNING:
This incremental was done for full backup dated <last full backup> and last full restored to this database is dated <earlier full backup>.
Do you want to continue?
THE ANSWER TO THIS QUESTION IS "YES".