How to prevent dual triggering of scheduled backups
Problem: Scheduled backups may sometimes start twice, once when you activate the backup set and again at the scheduled time....
This article is for all versions of Amanda Enterprise (AE).
Amanda provides a unique approach to scheduling that optimizes the load balancing of backups and simplifies the backup scheduling process.
For any backup cycle specified by the user, Amanda finds an optimal combination of full and incremental backups from all clients to make the total amount of backup data per run consistent from one backup run to another. To find such a balance, Amanda uses the following considerations:
- The total amount of data to be backed up as reported by each client for each backup level.
- The maximum time between full backups (dump cycle) specified by the user.
- The size of backup media available for each backup run.
This intelligent management method will result in the same backup size for each backup run resulting in a consistent backup window. This solves one of the key problems faced by backup administrators.
To calculate the optimal combination of backup levels, Every Amanda backup run starts with an estimate phase. Users can configure the type of estimation algorithm to be used on a per-client basis with options from a pure historical average to a mock backup run. Every Amanda client runs an optimized process to determine the change in data and the total size of that change. The estimate phase may take hours if there are many clients or if the clients have a large amount of data. After computing the size estimates, Amanda develops a backup plan for all clients and then begins the backup.
