Incremental forever and Disk Mediapools
Incremental forever backup in this document is defined as one initial full backup with subsequent Incremental backups over a long term.
Incremental forever functionality consist of the backups to the target device on the one hand and on the merging of the backups on the target device. The mechanism needs some preparations and some rules to be fulfilled in order to have a smooth production.
The rules to be fulfilled:
Incremental forever backup is possible on prepared Disc Pools only.
Incremental forever backup needs one initial full backup.
Incremental forever backups must not be mixed with regular full, differential and Incremental or database or systemstate backups in one Disc Pool.
These preparations must be done on the backup job definition and on the Disc mediapool definition.
The preparations on the Disc mediapool:
The preparations on the Disc mediapool consist of 2 additional Settings
The Disc mediapool is a text file on the backup Servers Install_Dir/Hiback/disk named for instance disc.0001. The name is free, yet it must fit in the 4.4 naming scheme, 4 alpha-numeric as prefix ans 4 numeric as Suffix.
In Version 4.5 you have to enter the additional Settings manually into the Disc mediapool file.
The preparations in the backup job definition:
the Update Job(s) -> [self] must be checked
the 1st mediapool must be a Disc mediapool which is prepared
the option complete Directory Incremental must be checked
the option add systemstate to backup must be unchecked
the option systemstate via vss must be unchecked
initially the Date Filter must be unchecked and the value must be empty
The Date Filter will be set and checked everytime the backup job runs successfully.
This is due to the Update Job(s) -> [self] setting. The Date Filter is crucial for the choice of the Files to be backed up in the next Incremental backup: the Date Filter and the modification Date are compared and if modification Date is newer or equal, the file is backed up.
Best practises for Incremental forever backup:
use more than one Disc mediapool if you want to backup a number of Clients in the Incremental forever mode.
use a round-robin scheme in the 1st mediapool job definition with respect to the Disc mediapools, eg. when you have defined 3 Disc mediapools prepared for Incremental forever and have 6 Clients to be backed up, let job1/job4 use pool1, job2/job5 use pool2, job3/job6 use pool3.
choose Disc mediapool retention schedule which definitely almost undisturbed by backups.