SAPDBA Specifying the File Size

SAP has default percentages for the growth in tablespaces in the SAPDBA profile init.dba (See tspadd_tspname). While these percentages are based on past experience, growth in tablespaces can vary widely, and you may want to change the default settings for your system. You can therefore enter a different file size than the default in the SAPDBA profile to reflect the actual growth you expect in the tablespace.

Guideline

You should size a new data file for that file to accommodate the growth of the tablespace for a long period. For a critical, rapidly growing tablespace, the file should be as large as possible. You also need to take the available storage space and the storage requirements of other tablespaces into account.

If you add many small files to a tablespace, you may need to reorganize the tablespace. This can be extremely time-consuming. Please also consider that you will have to shut down the R/3 System in order to reorganize the database. Reorganizing tablespaces with data files is the most complicated type of reorganization and should therefore be done as infrequently as possible. To avoid such situations, you should always add a sufficiently large file when extending a tablespace.

To minimize storage problems and in order not to reach the maximum number of files for the database system too quickly, SAP recommends that you do not set file sizes to values lower than those recommended below.

The following table contains tablespaces which should be monitored during productive operation:

Minimum File Sizes for Critical Tablespaces: Production

Tablespace	Minimum extension size (in MB) for data tablespace (D)	Minimum extension size (in MB) for index tablespace (I)
PSAPCLU	300	50
PSAPBTAB	300	200
PSAPSTAB	100	50
PSAPPOOL	100	50
PSAPPROT	100	50

Before transferring transaction data or starting production use of the system, each of these tablespaces must be extended with at least one file that is larger than the proposed minimum extension size.

If you work with client computers based on different hardware platforms, then you should also monitor PSAPLOADD/I or PSAPEL300D/I carefully.

Changes in these default values are entirely possible, especially - for example - when the EarlyWatch Service has determined other values to be more effective for your system.

During an SAP update or upgrade, in addition to the tablespaces listed above, you should check and - when necessary - extend the tablespaces listed below.

Minimum Extension Sizes for Critical Tablespaces: Update/Upgrade

Tablespace	Minimum extension size (in MB) for data tablespace (D)	Minimum extension size (in MB) for index tablespace (I)
PSAPDOCU	100	50
PSAPDDIC	50	20
PSAPSOURCE or PSAPES300	50	20

If possible, store I/O-intensive tablespaces each on separate hard disks.

If possible, select different mount points for a data tablespace and its index tablespace when you set up the database.

The SYSTEM tablespace can also be extended by SAPDBA. However, the size of the SYSTEM tablespace cannot be reduced after you have extended it.

A tablespace extension to PSAPTEMP can be cancelled by SAPDBA with the corresponding reorganization means. However, this is only possible if there are no temporary segments in PSAPTEMP (that is, you have to log off all the other users).

You can undo a tablespace extension to PSAPROLL only by means of irregular procedures using ORACLE functions. Excellent knowledge of ORACLE procedures is required!