How Backup Uses Backup Schedules

Backup uses a client's backup schedule to determine what level of backup operation to perform on a given day for the specified save sets. The time of day the backup operation begins is determined by the Start Time assigned to the Group resource with which the client save sets are associated.

Backup supports four different types of backup levels:

• Full - backs up all files, regardless of whether they have changed since the last backup operation.

• Level 1-9 - backs up files that have changed since the last lower numbered backup level.

• Incremental - backs up files that have changed since the last backup, regardless of the level.

• Skip - skips the scheduled backup.

(See "Backup Levels " for a detailed description of backup levels.)

Use the Schedules resource to customize backup schedules to best suit your needs. For example, some clients may have data you want to back up at level "full" every three days, with incremental backups in between. Other clients may have less critical data that only needs a full backup once a month, with incremental backups or level 1-9 backups on other days.

The time from one full backup to the next full backup is called a "backup cycle." Figure 3-2 illustrates a weekly backup cycle. In this example, a full backup is performed for a client each Sunday and incremental backups are performed the other days of the week.

Figure 3-2 Weekly Backup Cycle

You can use backup schedules to balance and stagger the load on your Backup server. Depending on the size of your network, you can apply the same schedule to all clients. For example, if no one works on Sunday and you want to run full backups on that day, you can apply the default schedule to all your clients. The default schedule tells Backup to perform full backups on Sunday and incremental backups the rest of the week. Figure 3-3 illustrates how the default schedule works for three clients: Client A, Client B, and Client C.

Figure 3-3 Using the Backup Default Schedule for Multiple Clients

Because full backups can take a long time, you may want to stagger them throughout the week. For example, you can apply a schedule that performs a full backup for Client A on Sunday, a second schedule that performs a full backup for Client B on Tuesday, and a third schedule that performs a full backup for Client C on Thursday. Figure 3-4 illustrates how you can use staggered backup schedules for multiple clients.

Figure 3-4 Staggered Weekly Schedules for Multiple Clients

When you balance and stagger the load on your Backup server, you can increase server efficiency. Using different start times for groups of clients also helps increase server efficiency.