SAP Basis

Unit 5: Fundamentals of Working with the Database ADM100
Storingthedataandloginfobackups:
The backed-up log information is deleted at operating system level so
that no disk space problems occur. If a disk crash occurs at time t5 and a
backup medium for the backup t3 is defective, an earlier data backup (in
this case, t1) must be used. To recover the database without data loss, it is
absolutely necessary to have all log info backups (in this case: t2 and t4)
since the data backup t1 and the log information as of 28. It is therefore
necessary to keep older data and log info backups.
Other remarks:
Some databases also require log information to be able to reset the
database. You should therefore ensure that you perform data and log
backups regularly.
Backup Cycle
There are various variants available for complete daily backup of the
data files, depending on the database. At least one online backup
should be made every day, with a subsequent complete backup of the
log information. The backup media used can be overwritten again after
28 days. This is a recommendation. Backups may be retained for much
longer periods in a company.
We recommend that the duration of a backup cycle is 28 days. This means
that the backup media for the data and log info backups are overwritten
after 28 days, at the earliest.
Figure 56: Recommended Backup Cycle
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