HP D2D100 Backup System - Manual (Page 19)

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 can be configured as one of the backup devices on the HP
D2D Backup System.)
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 RAID5 device, which offers the best combination of data protection and
capacity. It has four hard disks, but if one of the disks fails, no data is lost and the HP D2D Backup
System continues to operate correctly. (The failed disk should be replaced as soon as possible, as
described in “ Replacing the hard disk ” on page 115.)
Storage capacity
Physical storage
The physical storage capacity of the HP D2D Backup System 130 is 3.0 TB (3000 GB), of the HP
D2D Backup System 120 is 2.0 TB (2000 GB) and of the HP D2D Backup System 110 is 1 TB (1000
GB). However, in order to ensure a high level of data integrity, the disks use RAID 5 protection. This
reduces the available capacity but ensures that, in the event of a single disk failure in the device, there
will be no data loss.
Actual storage capacity is approximately:
• 2.25 TB for the HP D2D Backup System 130
• 1.5 TB for the HP D2D Backup System 120
• 750 GB for the HP D2D Backup System 110
You cannot add physical disk space, but you may be able to create some space. Options for creating
space, if the disks start to get full, 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.
Actual storage used
The default maximum cartridge size is 200 GB, but the HP D2D Backup System only allocates space as it
is required for backup. Individual backup jobs rarely use a whole cartridge and you are unlikely to use all
the available disk capacity. However, when configuring the HP D2D Backup System for extremely flexible
tape rotation schemes, it may be necessary to exercise a little care. You should take the following factors
into consideration to ensure that you do not over-commit physical storage space:
• The number of slots that you have configured in an autoloader. The default configuration is 8, but
you can edit that to be any number up to 24 (24 x 200 GB = 4.8 TB, which is greater than the
physical disk capacity. Therefore, you could not fill all of these slots with the capacity available.)
• The number of devices that you have created. It is possible to create up to six tape autoloaders,
each with 24 slots. You could not fill all of these slots with the physical disk capacity available.
Considerations when configuring cartridges and slots
Each slot configured commits 2 GB of physical disk space, regardless of what value has been configured
for the maximum cartridge size. The remainder of the configured maximum capacity is used only as
needed, but the initial 2 GB is permanently committed. Therefore, only configure the number of slots
D2D Backup System 19