HP 3000 Manuals HP 3000 Manuals
Choosing Full or Partial Backup Procedures ALLBASE/SQL provides the capability to either back up all the files in the DBEnvironment (full backup) or to back up only a subset of the files in the DBEnvironment (partial backup). You may choose full or partial backup when using either nonarchive or archive mode logging. If you choose to do a full backup, you can later do either a full recovery or a partial recovery from the full backup. If you do a partial backup, you can only do a partial recovery from that partial backup. The partial recovery can include all or a subset of the files contained in the partial backup. The first time you store your DBEnvironment you should do a full backup. On subsequent stores you should do a full backup if: your entire DBEnvironment is on one drive, the entire DBEnvironment is changing (being written to) between backups, or if you need to restore the entire DBEnvironment (in the case of disk failure). There are several reasons why you may want to do partial backups subsequent to your first full backup. If you have DBEFiles containing a table that is used infrequently, you may choose to attach the DBEFiles only when you use the table. Then you can detach DBEFiles when the table is not in use in order to save space on the system. (As an example, you could have a history file that is used only once a month when you transfer old account information from the account table into the history table. At that time, you use RESTORE PARTIAL to place the files on the system, attach the DBEFiles, and then transfer the historical information. Then you do a STORE PARTIAL or STOREONLINE PARTIAL to store only those files associated with the history table, detach the files and remove them from the system.) If your entire DBEnvironment is spread across several drives, it may be advantageous to do partial backups subsequent to your first full backup in the following two cases. In the first case, only a subset of the DBEnvironment files contains tables that are written to between backups. Then you can do partial backups of the files that are written to, and rely on the first backup to restore files that are read only. In the second case, only a subset of the DBEFiles contains essential data, and another subset of the files contains nonessential data (or data that can be derived from the essential data). In that case, you may choose to do a partial backup that includes the essential data, and then reconstruct the other data in the event of a hard crash.
NOTE If you do a STORE PARTIAL or STOREONLINE PARTIAL, it is your responsibility to store all the DBEFiles that contain tables that will be written to by your transactions. If you fail to do this, you will later be unable to restore your DBEnvironment to a consistent state.