Specifications

Using Backup Express for GuardianOS
Chapter 6 Data Protection 107
Backup Schemes
A backup schedule incorporates one of the following three types of operations
known as backup schemes:
• Base —
Backs up all target files on the Snap Server
•Differential —
Backs up all target files on the Snap Server that have changed since
the last base backup of the same name
• Incremental —
Backs up target files on the Snap Server that have changed since
the last backup of any type with the same name
Each backup scheme may have different parameters such as a different schedule or
a different output destination. However, the schemes must share the same input
source. Therefore, a backup definition includes all three backup schemes as well as
all the parameters governing them. Since they are part of the same backup
definition, they are referred to by the same name.
Sample Backup Schedules
The following three sample backup schedules illustrate how the three backup types
interact.
Network A has a base backup scheduled for every Sunday and an incremental
backup scheduled for all the other days of the week. All the backups are performed
at 2:00 am. If on Sunday at 1:00 am, all the data on the network is lost, it would take
7 tapes, 1 base plus 6 incrementals, to restore the entire enterprise.
Network B has a base backup scheduled for every Sunday and a differential backup
scheduled for every other day of the week. All the backups are performed at 2:00
am. If on Sunday at 1:00 am, all the data on the network is lost, it would take 2
tapes, 1 base plus 1 differential, to restore the entire enterprise.
Network C has a base backup scheduled for every Sunday, a differential backup
scheduled for every Thursday, and an incremental backup scheduled for every
other day of the week. All the backups are performed at 2:00 am. If on Sunday at
1:00 am, all the data on the network is lost, it would take 4 tapes, 1 base, 1
differential, and 2 incrementals, to restore the entire enterprise. Remember, the
differential backup copies all the data that has changed since the last base backup.
Therefore, the Thursday differential backup backs up all the data that was changed
on Monday, Tuesday, and Wednesday in addition to any data that changed on
Thursday.