CISA aspirants should understand various backup schemes as follow:
Full Backup- Every time data backup is taken of full database irrespective of earlier backup.
Incremental Backup-Backup is taken only of data changed since last backup (last backup can be either full backup or incremental backup).
Differential Backup-Backup is taken only of data changed since last full backup (last back to be full back-up only).
How to differentiate between Incremental & Differential Backup:
- Differential Backup
- Full backup taken at Monday
- On Tuesday backup taken for changes made after Monday’s backup
- On Wednesday backup taken for changes made after Monday’s backup (ignoring Tuesday’s backup)
- On Thursday backup taken for changes made after Monday’s backup (ignoring Tuesday’s & Wednesday’s backup)
- On Friday backup taken for changes made after Monday’s backup (ignoring Tuesday’s , Wednesday’s & Thursday’s backup)
- Incremental Backup
- Full backup taken at Monday
- On Tuesday backup taken for changes made after Monday’s backup
- On Wednesday backup taken for changes made after Tuesday’s backup
- On Thursday backup taken for changes made after Wednesday’s Backup
- On Friday backup taken for changes made after Thursday’s Backup
Storage Capacity for each backup Scheme:
Let us understand requirement for time and media capacity for various schemes for data storage:
-Full Backup- Requires more time and storage capacity as compared to other two schemes.
-Differential- Requires less time and storage capacity as compared to full backup but more time and storage capacity as compared to Incremental.
-Incremental- Requires less time and storage capacity as compared to other two schemes.
Restoration Capability for each backup Scheme:
Let us understand effectiveness of various schemes in case of data restoration:
-Full Backup- Fastest of all three schemes.
-Differential- Slower than Full backup but faster than incremental.
-Incremental-Slowest of all three schemes.