HP D2D100, Руководство пользователя

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12 Hard disk replacement
In this chapter:
• “ RAID 5 ” on page 157
• “ How do I know a disk has failed? ” on page 157
•
“ Electrostatic discharge information ” on page 161
• “ Replacing the hard disk ” on page 161
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:
• 2.25 TB for the HP D2D Backup System
How do I know a disk has failed?
The Web Management Interface identi fi es failed or predictive failed disks. The HP D2D Backup System
operates correctly with one failed disk. It is important to replace a failed or predictive 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 RAID status has failed, but it is recoverable.
This means that one disk has failed.
D2D Backup System HP D2D2503
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