Setting Up Volume Sets and Volumes for Logical-Log Backup (ON-Ar (SAP Library - SAP Database Guide: Informix (BC-DB-INF-DBA))

Setting Up Volume Sets and Volumes for Logical-Log Backup (ON-Archive)

Use

Before you can back up the logical log of your Informix database, you must define at least one volume set and volume.

Procedure

If you are using automatic backup with the script logevent.sh , the script expects the volume set LOGTAP and its volumes (although it is possible to edit logevent.sh to use another volume set).

If you are using automatic backup with the DBA Planning Calendar of CCMS in the SAP System, you can specify whichever names you like for volume sets and volumes. For more information, see:

Backing Up the Logical Log in the DBA Planning Calendar (Informix)

Backing Up the Logical Log (Automatic) in the DBA Planning Calendar (Informix)

If you are using continuous backup, you can use either tape-based or disk-based backup as follows:

Tape-based volume sets for continuous backup

You can use the SAP scripts arcprep and arcvolum (see final step in this procedure), as they create tape-based volume sets. The number of volumes required in a tape-based volume set for logical-log backup depends on how large your logical log is and your tape retention cycle (that is, how long you plan to keep the backup tapes before they are overwritten – this should be 28 days or longer).

Disk-based volume set for continuous backup

A disk-based volume set is used as a temporary storage area for continuous backup. You should define a single volume in the disk volume set LOGDIR . You do not need to have more than one volume for a disk volume set, unlike tape volume sets that typically contain more than one volume (that is, tape).

Your disk-based volume must be able to accommodate at least the entire logical log. SAP recommends that you have approximately one GB storage in the directory containing the volume. This is normally more than enough for one save set (typically around 400 MB, that is, 40 logical-log files of 10 MB each). One GB enables you to store two save sets easily, in case you fail to get the first save set copied to tape before the next backup.

Recommendation

SAP recommends you to use tape-based continuous backup. See Choosing Continuous Logical-Log Backup (ON-Archive).

Depending on your requirements identified in the steps above, set up volume sets and volumes in either of the following ways:

With the SAP scripts (recommended)

You should use the SAP scripts since they help you to define the required volume sets and volumes on tape, as follows:

arcprep generates the volume set LOGTAP for archiving and a series of associated volumes labeled LOGT1 , LOGT2 , LOGT3 ... up to the number you specify.

arcvolum defines additional volumes in pre-existing volume sets, if required.

Refer to Setting Up Volume Sets and Volumes for ON-Archive with SAP Scripts.

Manually

Refer to Setting Up Volume Sets and Volumes for ON-Archive Without SAP Scripts. If you are backing up to a temporary storage area on disk, then you must define the volume set yourself.

Result

You have set up volume sets and volumes, which is an essential requirement for logical-log backup.

See also:

Informix documentation