Mail Slots (Import/Export Elements); Physical Tape Drives; Storage Capacity; Raid - HP StorageWorks D2D100 - Backup System User Manual

support multiple tape drives whereas an autoloader only has one tape drive. This provides considerable
storage capacity and full support for tape rotation strategies. (It may be necessary to upgrade your
backup application to support libraries.)

Mail slots (import/export elements)

A mail slot is a term borrowed from tape terminology to identify a dedicated slot that is used specifically to
import and export cartridges. They are sometimes called import/export elements by backup applications.
Backup applications that support this feature move cartridges from the mail slot when the user runs an
Export job, and look for cartridges in the mail slot when the user runs an Import job.

Physical tape drives

A physical tape drive is a tape drive that is attached to the HP D2D Backup System or the host computer,
so that data can be moved from the HP D2D Backup System and stored offsite. (It should not be confused
with the tape drive device that is attached to the library device on the HP D2D Backup System (see
"Devices (Configuration)" on page 69.)

RAID

RAID stands for Redundant Array of Inexpensive (or Independent) Devices, which is a data storage
scheme that divides data among multiple hard drives, increasing data reliability and throughput. The
HP D2D Backup System is a RAID 6 device, which offers the best combination of data protection and
capacity for disk arrays. It provides protection against double disk failures and failures while a single
disk is rebuilding. The failed disk should be replaced as soon as possible.

Storage capacity

Physical storage

The physical storage capacity of the HP D2D Backup System is 4.5 TB (6 x 750 GB) or 9.0 TB (12 x
750 GB). However, in order to ensure a high level of data integrity, the disks use RAID 6 protection.
This reduces the available capacity but ensures that, in the event of a disk failure in the device, there
will be no data loss.
Actual storage capacity is approximately:
• 3 TB for the 6–disk HP D2D Backup System
• 7.5 TB for the 12–disk HP D2D Backup System
Data deduplication is enabled by default for each library device. This eliminates duplicate data from
backups and means that more histories of data can be stored and retained for longer on each library.
See also "Data deduplication" on page 21.
If you have the 6–disk model, it is possible to extend disk space by purchasing and installing the 6–disk
extension pack. This more than doubles the storage capacity. Other options for creating space are:
• Review your backup jobs to see if you can reduce the size of backup or retention time.
• Use the backup application job settings to overwrite or erase data.
• Export cartridges to physical tape.

Tape rotation strategies

Tape rotation strategies determine when backups are run, the number of cartridges that are required and
how they are reused. The HP D2D Backup System is a very flexible device that can easily be incorporated
into most tape rotation strategies. If your organization does not yet have a tape rotation strategy in place,
see "Tape rotation example with
20
Before you start
deduplication" on page 22 for example configurations.