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SAP AG November 2002
The external backup ID is written to logs dbm.knl (backup history [Page 126]) and dbm.ebf
during backup.
The external backup ID is used during a restore to request the desired backup. The external
backup ID is displayed before the restore operation, and can be corrected if necessary. To do
this, the Database Manager [Page 133] transfers the external backup ID to the DBM Server
as a command parameter, and the DBM server forwards this to the external backup tool.
External Backup Medium
See Name of an external backup mediums [Page 145]
External Backup Tool
Backups [Page 126] can also be carried out using external backup tools on external backup
media.
A detailed description of the use of external backup tools can be found in the following
documentation: External Backup Tools: SAP DB [See SAP DB Library].
See also:
External backup medium [Page
138]
Name of external backup medium [Page
145]
External backup ID [Page 137]
Group of Parallel Backup Media
You can carry out a parallel backup [Page 126] to several backup media [Page 127] and
recover data from parallel backup media. For this purpose you define a group of parallel
media that is identified by a single, grouped media name.
Parallel backup media are simultaneously written or read by the database instance. This
increases data throughput - and thus the speed of backup or restore.
I/O Buffer Cache
One important cache [Page 129] of a SAP DB database is the I/O buffer cache.
When the database system is started, the I/O buffer cache is created in the main memory in
accordance with the size entered in the database parameter CACHE_SIZE [Page 81] and is
managed via the page pool [Page 146].
A certain number of pages of the I/O buffer cache are made available to the converter [Page
129]. The remaining pages are made available to the data cache [Page 130].
The converter requires more pages during database operation, the distribution of all I/O buffer
cache pages among the converter and data cache is dynamically changes to meet this
requirement.
User Manual: SAP DB 138