By default, local storage and the local storage cache use the same default storage location as defined in “Setting the default local storage path”.

However, local storage and the local storage cache have the following differences:

.Data is sent to the local storage location at the same time the data is processed by DS-Client to be sent to the DS-System. Data is sent to the local storage cache only when the connection to the DS-System is not available.

By default, data is saved in the local storage as regular generations in compressed format, but is not encrypted. Data is saved in the local storage cache as a master generation that includes additional information that determines which blocks of data from within that file are required for delta generations. When the connection between the DS-Client and DS-System is reestablished, DS-Client moves the required files from the local storage based on the backup set configuration in the format they were stored in the local storage cache (encrypted and compressed) and sends only delta generations to DS-System. As a result, DS-Client can still process master/delta (Incremental forever) generations when performing backup using the Local Storage Cache option. Similarly, the local storage can include encrypted as well as unencrypted data, depending on when the files were processed during a particular backup activity. Files are released from the local storage cache one-by-one as their successful transmission to the DS-System is confirmed between DS-System and DS-Client.

The configured number of generations for the items in a backup set does not take effect when data is sent to the local storage cache. 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 if DS-System is unavailable and/or DS-Client did not finish moving the data from the Local Storage Cache 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 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.

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

DS-Client performs basic checks to ensure the validity of the files from the local storage cache on transfer to DS-System. If DS-Client determines that a file is corrupt, it removes the file information from the DS-Client database and determines if the files needs to be backed up again in the next backup session.

If a backup set is marked as out-of-sync and DS-Client cannot connect to DS-System to perform synchronization, then DS-Client cannot run backup to the local storage cache. DS-Client administrators must ensure that sufficient local storage disk space is available to accommodate all data in the local storage or local storage cache for all the configured backup sets. If data exists in the local storage cache for a selected backup set, that data must first be transferred to DS-System, and only afterwards can DS-Client perform subsequent backups for that backup set directly to DS-System. Suspending a backup set configured with the local storage cache will not allow the local storage cache copy process to be triggered and to connect to DS-System to move the data.