Define whether files are to be compressed (software or hardware compression).
Syntax: compress = no|yes|hardware|only
Notes on Software Compression (Without Starting a Backup) with compress = only
If you use tape units that support hardware compression, SAP recommends that you perform software compression of the entire database with parametercompress = only at least once a month, so that the current compression rate can be determined for each of the data files. When you use this parameter, backup is not started.
If you do not want to compress the entire database, you should at least compress those database files where a lot of changes take place. To determine these files, compare the compression rates of all files in two subsequent compression operations. The compression rates for files that have not changed will probably remain constant in the future, as well.
After extreme database changes (reorganization, release upgrade, transfer of large quantities of data), you should always start the software compression in order to determine the compression rates for the entire database.
The setting of parameterbackup_dev_type is not relevant for this activity, since no backup is started.
Check the setting of option-b 12 in command compress_cmd.