The Local Storage Cache feature enables DS-Clients to perform backup on a local attached disk or UNC path accessible by the DS-Client software and send the data to DS-System later when DS-System service becomes available. Backup sets must be configured to use this option. The Local Storage Cache option is available for backup sets if DS-Client has the Local Storage tool enabled (from DS-System).

If backup sets are configured with the Local Storage Cache option, DS-Client will send data to the Local Storage Cache when the following occurs:

If a DS-Client tries to connect to a DS-System and cannot establish the connection, DS-Client will process the data and save it in the Local Storage Cache buffer. Once DS-Client is able to connect to DS-System, a Local Cache Copy process will be triggered which will send to DS-System each generation of the required files in the required format: i.e. master/delta/regular.

If DS-Client established a connection with DS-System for this backup set and the backup activity was interrupted, DS-Client will run a synchronization activity and then proceed with the Local Cache Copy process when connection to the DS-System is re-established.

The Local Cache Copy process is considered as a backup activity (by DS-System) with the same priority and the same backup set locking rules.

Data is sent to the Local Storage Buffer at the same time when data is being processed to be sent to DS-System (there is an established connection between DS-Client and DS-System). Data is sent to the Local Storage Cache Buffer, ONLY when connection to the DS-System is NOT available.

By default, data is saved in the Local Storage Buffer compressed, but not encrypted (configurable), and as "regular" generations of the files. Data is saved in the Local Storage Buffer buffer is compressed and encrypted as "master" generations of the files.

Data is saved in the Local Storage Cache buffer as a master generation that includes additional information that determines which blocks of data from within that file are required for delta generations.

When connection between DS-Client and DS-System is established, DS-Client will move the required files to the Local Storage Buffer (based on backup set configuration) in the format they were stored in the Local Storage Cache Buffer (encrypted and compressed) and will send only "delta" generations to DS-System (when applicable).

As a result, DS-Client can still process Master/Delta (Incremental forever) when performing backup using the Local Storage Cache Option. Similarly, the Local Storage Buffer may include encrypted as well as unencrypted data, depending on when the files were processed during a particular backup activity.

Files are removed from the Local Storage Cache Buffer or moved to the Local Storage Buffer when they have been successfully transferred to DS-System. File are released from Local Storage Cache Buffer one-by-one as their successful transmission to the DS-System is confirmed between DS-System and DS-Client.

An initial backup session does not process data for Local Storage Buffer or Local Storage Cache Buffer.

The configured number of generations for the items of a backup set does not take effect when data is sent to the Local Storage Cache Buffer. For example: A backup set is configured to store a maximum of three generations of data on the DS-System Online Storage. It can store more than three generations of data in the Local Storage Cache Buffer if DS-System is unavailable and/or DS-Client did not finish moving the data from the Local Storage Cache Buffer to the DS-System. All generations will be sent to DS-System whenever possible as regular generations or Master/Delta generations and DS-System will process them as it would process any generations sent directly to it (e.g. it will mark generations as recycled when required, it will trigger reconstruction when required, etc.).

By default, the Local Storage Buffer will store the latest generation of all the files processed for a backup set. However, if Local Storage Retention is enabled and assigned to a backup set with Local Storage Options enabled, DS-Client will store all generations that meet the criteria specified in the Local Storage Retention rules in the Local Storage Buffer.

DS-Client can restore data directly from the Local Storage Buffer and can connect to DS-System to retrieve only data that does not exist in the Local Storage Buffer (configure this behavior from the Restore Wizard, before triggering the restore activity). Data from the Local Storage Cache Buffer cannot be restored until it has been transferred to DS-System.

DS-Client can perform basic checks to ensure the validity of the files from the Local Storage Cache Buffer when the files are transferred to DS-System. As a result of these checks, if DS-Client determines that the files are corrupted, it will remove the file information from the DS-Client database and will try to determine if the files need to be backed up again during the subsequent backup session.