Interstage Shunsaku Data Manager Operator's Guide - Microsoft(R) Windows(R) 2000/ Microsoft(R) Windows Server(TM) 2003 - - UNIX -

5.1.2 Backup Cycle

The interval between regular backups is referred to as the 'backup cycle'.

If a backup is taken every morning, the backup cycle is one day.

The backup cycle should be determined at design time, taking the following factors into account:

• Recovery time

  The information that accumulates in the operation log file is used for restoring the system. If a large number of operations accumulate in the operation log file between backups, the large size of the operation log may cause any recovery process to take a long time, which will delay the time before normal operations can recommence.

  For this reason, the time needed to perform a recovery operation should be taken into account when determining the backup cycle.

• Capacity of the disk where the operation log file is located

  The backup cycle should be used to determine the size of the disk where the operation log file will be stored. The operation log file contains update log data that accumulates between the end of one backup for the director data file and the beginning of the next, so the operation log file must be large enough to store the update log data with room to spare. For example, if a backup is taken every day, the capacity of the operation log file needs to be larger than that is needed to store a day's update log data.

• If the directory where the operation log file is located is too small, it will not be possible to update data. If this is the case, back up the director data file, discard the operation log file and then shorten the director data file backup cycle.

Refer to D.3.2 The Size of Operation Log Files for more information on the capacity of the operation log file.