replacement HP D2D Backup System without hard disk drives may be supplied.
The HP D2D Backup System Backup System is a RAID 5 configured device with four disks. No other RAID

configurations are supported.

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HP D2D Backup System 110 has four 250 GB disks

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HP D2D Backup System 120 has four 500 GB disks

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HP D2D Backup System 130 has four 750 GB disks

RAID 5

RAID 5, Distributed Data Guarding, offers the best combination of data protection and usable capacity.

RAID 5 stores parity data across all the physical drives in the array and allows more simultaneous read

operations and higher performance than data guarding (RAID 4). If a drive fails, the controller uses the

parity data and the data on the remaining drives to reconstruct data from the failed drive. The system

continues operating with a slightly reduced performance until you replace the failed drive. RAID 5

requires an array with a minimum of three physical drives. For the HP D2D Backup System, which has

four disks, 25% of the total logical drive storage capacity is used for parity data.
This means that actual storage capacity is approximately:

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2.25 TB for the HP D2D Backup System 130

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1.5 TB for the HP D2D Backup System 120

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750 GB for the HP D2D Backup System 110

How do I know a disk has failed?

The Status and Disk Status LEDs show amber, if a disk fails. Use the Web Management Interface to help

you identify the disk that has failed. The HP D2D Backup System operates correctly with three disks, but

protection is limited. It is important to replace the failed disk as soon as possible. Any subsequent disk

failure will result in complete data loss.
In the following Summary page example you can see that one disk has failed.

D2D Backup System

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