How to prevent more than one full backup per Backup Cycle

This article is for Amanda Enterprise (AE) 

Info Type: Tip

Info Description:

When there are fewer backup entries than Backup Cycle days, Amanda works over time trying to balance out the backup load causing some entries to be backed up in full much more frequently than once per Backup Cycle. If this is occurring, you will see messages for such backup entries as below in the NOTES section of the Amanda report as shown on the Report|summary page:

planner: Full dump of localhost:/var promoted from 14 days ahead.

The action of running a full backup before it is due is called “promoting”. To “turn off” promoting of a backup entry, you can use the “maxpromoteday” Amanda parameter. This must be currently performed oustide of ZMC by manually editing the disklist.conf file for a backup set.

The disklist.conf file is found in the directory /etc/amanda/<backup_set_name>/ for each backup set.  Each backup entry in this file starts with its hostname, a disk name, the backup directory, and then has all the parameters for this backup entry on their own line in between curly braces.  Place “maxpromoteday 0” on its own line as a new parameter for a backup entry, such as:

hostname "diskname" "disk_directory" { 

.

.

.

maxpromoteday    0
} 

This edit will turn off promoting for this backup entry. This can be repeated for other backup entries in the same and other backup sets.

If you are curious why Amanda promotes entries: one of Amanda’s features is to balance the backup load over the duration of the Backup Cycle.  The Backup Cycle is the period of time in days over which Amanda will perform at least one full backup of every backup entry.  The way Amanda can achieve  this is to “promote” certain backups to a full backup before it is due. When there are fewer backup entries than Backup Cycle days, Amanda works over time trying to balance out the backup load causing some entries to be backed up in full much more frequently than once per Backup Cycle.

There is an Amanda parameter called “maxpromoteday” that tells Amanda the maximum amount of days it can perform a full backup of a backup entry before that entry is due for another full backup. Specifying “maxpromoteday 3” for a backup entry, for instance, tells Amanda not to promote a full backup of this backup entry earlier than 3 days ahead of when it is due.  If this parameter is set to 0, Amanda will not promote this backup entry to a full backup ahead of schedule at all.

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