Example 3: Two policies, different schedules, multiple clients, one destination volume

This strategy uses two NetBackup policies to back up two sets of clients to the same destination volume. One policy schedules backups once a day; the other policy schedules backups twice a day.

Configuration: Five clients are to be backed up. Using one policy (policy_1) you back up client1, client2, and client3 once a day. Using another policy (policy_2), you back up client 4 and client5 twice a day. Both policies specify that all five clients are backed up to the same destination volume.

Result: The first scheduled backup of policy_1 creates backup copies for client1, client2, and client3. Data ONTAP makes a Snapshot copy to preserve the three backups.

The first scheduled backup of policy_2 creates backup copies for client4 and client5. Data ONTAP makes another Snapshot copy, preserving not only these two backups, but also the three backups of clients 1 through 3 made by the first scheduled backup of policy_1; therefore, Data ONTAP deletes the first Snapshot copy and keeps the second Snapshot copy.

After the second scheduled backup of policy_2, backups of clients client4 and client5 have been made once again and another Snapshot copy made. In this Snapshot copy, client1, client2, and client3 are the same as the backups in the first Snapshot copy, but the backups for client4 and client5 are different; therefore, Data ONTAP keeps this Snapshot copy as well, for a total of two Snapshot copies.

At the end of the day, there are two Snapshot copies that store seven unique backups of the five clients on the same destination volume. The first Snapshot copy contains unique updates to all five clients, while the second Snapshot copy contains three unchanged backups of client1, client2, and client3, and two unique backups of client4 and client5.

After five days, 35 unique backups of the 5 clients are stored in 10 Snapshot copies. Visually, this appears like the following table.

Archival Snapshot copy	Contains...
snapshot1—day 1	client1, client2, client3, client4, client5
snapshot2—day 1	client1 (unchanged), client2 (unchanged), client3 (unchanged), client4, client5
snapshot3—day 2	client1, client2, client3, client4, client5
snapshot4—day 2	client1 (unchanged) , client2 (unchanged), client3 (unchanged), client4, client5
snapshot5—day 3	client1, client2, client3, client4, client5
snapshot6—day 3	client1(unchanged) , client2 (unchanged), client3 (unchanged), client4, client5
snapshot7—day 4	client1, client2, client3, client4, client5
snapshot8—day 4	client1(unchanged) , client2 (unchanged), client3 (unchanged), client4, client5
snapshot9—day 5	client1, client2, client3, client4, client5
snapshot10—day 5	client1 (unchanged) , client2 (unchanged), client3 (unchanged), client4, client5

Maximum number of backups preserved in the volume: Using this strategy, the 250 Snapshot copy limit is reached in 125 days. Backups of client4 and client5 are present in all of the Snapshot copies, while backups of client1, client2, and client3 are present in half of the Snapshot copies. For simplicity, let us suppose that Snapshot copies do not expire. By the time the 250 Snapshot copy limit is reached, 250 Snapshot copies contain backups of client4 and client5 and 125 Snapshot copies contain backups of client1, client2, and client3.

Expiring backups to remove the oldest Snapshot copies: At the end of the 125th day, before taking any more backups, you should expire (delete) the oldest two backups of the five clients from NetBackup. This deletes the oldest two Snapshot copies, reducing the total number of Snapshot copies to 123. Now, you can take yet another backup of all five clients and save them in a couple of subsequent Snapshot copies. After day 125, you must expire the oldest two backups of all five clients daily to have two Snapshot copies available for future backups to the five clients.

Parent topic: How to manage consumption of Snapshot copies