HP StoreOnce D2D4324 HP D2D25xx, 41xx and 43xx Backup System user guide (EH985 - Page 136

Hard disk replacement, RAID

Page 136 highlights

14 Hard disk replacement In this chapter: • RAID • How do I know a disk has failed? • Replacing a hot-plug hard disk • After replacing the failed disk RAID RAID 6 RAID 6 provides protection against double disk failures and failures while a single disk is rebuilding. The following HP StoreOnce Backup Systems are RAID 6 devices. • HP D2D4312 and HPD2D4324 Backup Systems • HP D2D4106 and HP D2D4112 Backup Systems The HP StoreOnce Backup System head unit is protected by a RAID 6 volume, and each Capacity Upgrade Kit is protected by a separate RAID 6 volume. Therefore the head and each Capacity Upgrade Kit can experience a double disk failure without incurring a data loss. These HP StoreOnce Backup Systems also have an online spare disk on each shelf, which will automatically be incorporated into the RAID if a disk fails. This means that actual storage capacity is approximately 75% of the physical storage capacity for the main unit and each Capacity Upgrade Kit connected to it. • 18 TB for the HP D2D4324 Backup System and 18 TB for each of up to three Capacity Upgrade Kits • 9 TB for the HP D2D4312 Backup System and 9 TB for each of up to three Capacity Upgrade Kits • 9 TB for the HP D2D4112 Backup System and 9 TB for an attached Capacity Upgrade Kit • 4.5 TB for the HP D2D4106 Backup System and 4.5 TB for an attached Capacity Upgrade Kit RAID 5 The following HP StoreOnce Backup Systems are RAID 5 devices. • HP D2D2504 Backup Systems • HP D2D2502 Backup Systems RAID 5 stores parity data across all the physical drives in the array. 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 StoreOnce 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: • 1.5 TB for the HP D2D2502i Backup System • 3.0 TB for the HP D2D2504i Backup System 136 Hard disk replacement

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14 Hard disk replacement
In this chapter:
RAID
How do I know a disk has failed?
Replacing a hot-plug hard disk
After replacing the failed disk
RAID
RAID 6
RAID 6 provides protection against double disk failures and failures while a single disk is rebuilding.
The following HP StoreOnce Backup Systems are RAID 6 devices.
HP D2D4312 and HPD2D4324 Backup Systems
HP D2D4106 and HP D2D4112 Backup Systems
The HP StoreOnce Backup System head unit is protected by a RAID 6 volume, and each Capacity
Upgrade Kit is protected by a separate RAID 6 volume. Therefore the head and each Capacity
Upgrade Kit can experience a double disk failure without incurring a data loss.
These HP StoreOnce Backup Systems also have an online spare disk on each shelf, which will
automatically be incorporated into the RAID if a disk fails. This means that actual storage capacity
is approximately 75% of the physical storage capacity for the main unit and each Capacity Upgrade
Kit connected to it.
18 TB for the HP D2D4324 Backup System and 18 TB for each of up to three Capacity
Upgrade Kits
9 TB for the HP D2D4312 Backup System and 9 TB for each of up to three Capacity Upgrade
Kits
9 TB for the HP D2D4112 Backup System and 9 TB for an attached Capacity Upgrade Kit
4.5 TB for the HP D2D4106 Backup System and 4.5 TB for an attached Capacity Upgrade
Kit
RAID 5
The following HP StoreOnce Backup Systems are RAID 5 devices.
HP D2D2504 Backup Systems
HP D2D2502 Backup Systems
RAID 5 stores parity data across all the physical drives in the array. 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 StoreOnce
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:
1.5 TB for the HP D2D2502i Backup System
3.0 TB for the HP D2D2504i Backup System
136
Hard disk replacement