How Backup Uses Backup Groups

The client save sets in each Backup group begin their automatic scheduled backups according to the start time of the group. You can balance the backup loads by taking the client's backup schedule into account when you decide which clients to include in a specific group. (Refer to "Schedule Configuration " for more information about creating schedules that vary the days that different clients perform full backups.)

Figure 3-1 illustrates how Backup uses backup groups to back up multiple client save sets.

Figure 3-1 How Backup Uses Groups to Back Up Multiple Clients

In this example, three client machines, Oak, Elm, and Fir, are part of the group named Weekly Full, which starts its automatic scheduled backup at midnight. Client Oak runs a full backup of all its save sets every Monday and incremental backups of its save sets on the other days; client Elm runs a full backup of all its save sets on Tuesday and incremental backups on the other days; and client Fir runs a full backup of all its save sets on Wednesday and incremental backups on the other days of the week. Because each client runs its full backup on a different day of the week, the server is not overloaded.

The second group, "Accounting," illustrates how you can group clients by department. Group Accounting contains client machines Birch and Pine and starts its backups at 7:00 p.m., when the machines in the Accounting Department are available for backup. Although the two client machines run full backups on the same day, machine Pine is scheduled to back up only the /usr/home save set; all the save sets on machine Birch are backed up. By estimating how long a backup takes, you can determine what start time to set for the next group.

The save sets from each group are written to appropriate volumes mounted on storage devices. Backup uses pools of volumes to organize, track, and store save sets; it uses groups to determine what time clients start their scheduled backups.