Backup to long-term storage is called the PreStore process. The PreStore process initiates prescheduled study backups to DLT removable media (or any other media supported by NetBackup). The Long-Term Storage Manager saves new images in a temporary online buffer (LTSMs cache) until the PreStore process copies the images to permanent media. For every study, there are at least two copies in existence at all times.
Before the storage process begins, the system determines which of the studies need to be backed up, according to the following criteria:
The arrival time of a study at the LTSMs. This parameter is used to prevent incomplete studies from being stored.
Whether all of the study images reside in the LTSMs cache. If all of the images reside in the cache, the study is listed for immediate backup. A second list is then created that includes all of the incomplete studies that must be bound with new images before they can be stored. To minimize backup time, both lists are executed simultaneously, so that every fetched study is immediately stored on removable media.
The PreStore operation automatically copies the images ready for long-term storage to a media volume from the unused media pool in the library archive. If there is no new media available, the PreStore process halts and requests a new media volume through the LTSMs Web interface.
After the PreStore process is completed, and if the system is configured to work without the mirroring feature, the LTSMs cache is cleaned automatically.