This strategy uses two NetBackup policies to back up two sets of clients to two FlexVol volumes. One policy schedules backups once a day; the other policy schedules backups twice a day.
Configuration: Five clients, client1 through client5, are 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. The clients in policy_1 are backed up to FlexVol volume volA and the clients in policy_2 are backed up to FlexVol volume volB.
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. After five days, 15 unique backups of 3 clients are stored in 5 Snapshot copies on FlexVol volA. Visually, this appears like the following table.
The first scheduled backup of policy_2 creates backup copies for client4 and client5. Data ONTAP takes a Snapshot copy to preserve the two backups. After the second set of backups scheduled for policy_2 finishes, backups for the updated client4 and client5 are created. Data ONTAP takes a second Snapshot copy to preserve the updated backups. The earlier Snapshot copy cannot be deleted because they contain unique client updates; therefore, two Snapshot copies per day are kept.
After five days, 20 unique backups of the 2 clients are stored in 10 Snapshot copies on FlexVol volB. Visually, this appears like the following table.
Maximum number of backups preserved in the volumes: FlexVol volume volA, saving one archival Snapshot copy a day, reaches the maximum Snapshot copy limit after 250 days. FlexVol volume volB, saving two Snapshot copies a day, reaches the limit after 125 days. The advantage of using separate FlexVol volumes is that you can direct backups with different backup frequencies to the same aggregate and store 250 unique updates before you have to start expiring old backups.
Expiring backups to remove the oldest Snapshot copies: At the end of the 250th day, FlexVol volume volA reaches the recommended maximum number of 250 Snapshot copies. You should expire (delete) the oldest backup of each of the three clients from NetBackup after the 250th day, thereby reducing the number of Snapshot copies to 249 and enabling Data ONTAP to take a Snapshot copy the next day. The maximum retention period for the clients backed up to FlexVol volume volA is 250 days (to prevent running out of Snapshot copies in the volume).
At the end of the 125th day, FlexVol volume volB reaches the recommended maximum number of 250 Snapshot copies. You should expire (delete) the oldest two backups of each of the two clients from NetBackup after the 125th day, thereby reducing the number of Snapshot copies to 248 and enabling Data ONTAP to take two Snapshot copies the next day. The maximum retention period for the clients backed up to FlexVol volume volB is 125 days.