HP StoreOnce D2D4324 HP StoreOnce Backup System Concepts and Configuration Gui - Page 109
Tape Offload, Terminology, Direct Tape Offload
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15 Tape Offload Terminology Direct Tape Offload This is when a physical tape library device is connected directly to the rear of the StoreOnce Backup system. This offload feature is not currently supported on HP StoreOnce Backup system. Backup application Tape Offload/Copy from StoreOnce Backup system This is the preferred way of moving data from a StoreOnce Backup system to physical tape. The data transfer is managed entirely by the backup software, multiple streams can be copied simultaneously and StoreOnce NAS, Catalyst store and VTL emulations can be copied to physical tape. Both the StoreOnce Backup system and the physical tape library must be visible to the backup application media server doing the copy and some additional licensing costs may be incurred by the presence of the physical tape library. Using this method, entire pieces of media (complete virtual tapes or NAS shares) may be copied OR the user can select to take only certain sessions from the StoreOnce Backup system and copy and merge them onto physical tape. These techniques are known as "media copy" or "object copy" respectively. All copies of the data are tracked by the backup application software using this method and it is the tape offload method HP recommends. When reading data in this manner from the StoreOnce Backup system the data to be copied must be read from the StoreOnce appliance and "reconstructed" then copied to physical tape. Just as with the backup process - the more parallel backup streams to the StoreOnce appliance the faster the backup will proceed, Similarly the larger the number of parallel reads generated for the tape copy, the faster the copy to tape will take place - even if this means less than optimal usage of physical tape media. Scheduling tape offload to occur at less busy periods, such as weekends, is also highly recommended, so that the read process has maximum I/O available to it. Backup application Mirrored Backup from Data Source This again uses the backup application software to write the same backup to two devices simultaneously and create two copies of the same data. For example, if the monthly backups must be archived to tape, a special policy can be set up for these mirror copy backups. The advantage of this method is that the backup to physical tape will be faster and you do not need to allocate specific time slots for copying from StoreOnce Backup system to physical tape. All copies of the data are tracked by the backup application software. Terminology 109