
13 Hard disk replacement
In this chapter:
•
“Replaceable parts” on page 113
•
“How do I know a disk has failed?” on page 113
• “Electrostatic discharge information ”onpage115
• “Replacing the hard disk” on page 115
Replaceable
parts
The only fun
ctional par ts that can be replaced i n the HP D2D Backup System B ackup System are the
hard disks. If the unit fails for any other reason than hard disk failure and it is still under warranty, a
replacement HP D 2D Backup System without hard disk drives may be supplied.
The HP D2D Ba
ckup System Backup System is a R AI D 5 configured device with four disks. No other RAID
configurati
ons are supported.
• HP D2D Backup System 110 has four 250 GB disks
• HP D2D Backup System 120 has four 500 GB disks
• HP D2D Back
up 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 a cross all the physical drives in the array and allows more simultaneous read
operations and higher performance than data guarding (RAI D 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. R A ID 5
requires an array with a minimum of three physical drives. For the HP D2D Ba ckup System, which has
four disks, 25 % of the total logical drive stora ge capacity is used for parity data.
This means that actual storage capacity is approximately:
• 2.25 TB for the HP D2D Backup System 130
• 1.5 TB for the HP D2 D Backup System 120
• 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 Ba ckup System operates correctly with three disks, but
protection is limited. It is impor tant to replace the failed disk as soon as possible. Any subsequent disk
failu
re will result in complete data loss.
In the following Summary page example you can see that one disk has failed.
D2D Backup System
113
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