NEC NovaScale R480 E1 User Manual page 116

Virtual Disk
A Virtual Disk is a logical drive defined in a Disk Group. It is recognized as a physical drive by the OS. The authorised
number of virtual disks is up to 16 per disk group, or up to 64 per controller.
The figure below shows a sample configuration in which the Onboard RAID Controller (MegaRAID ROMB) is
connected to three HDDs, creating one Disk Group. Two RAID5 virtual disks (VD) are defined in the Disk Group.
VD0-1
20GB
VD1-1
16 GB
HDD 1
(36 GB)
Parity
Parity implies data redundancy. A single set of redundant data is created from the data saved in several HDDs (at least
two). The redundant data thus created is used for data recovery when a HDD is defective.
Hot-Swap
Hot-swapping enables a HDD to be removed (or replaced) under system operation.
Hot-Spare
The hot-spare is prepared as an auxiliary HDD substituting for a defective HDD included in a logical drive which is
configured at a redundant RAID level. Detecting a HDD fault, the system disconnects the HDD (or makes it offline)
and starts rebuild using the hot-spare.
NOTE:
For a standby rebuild (rebuild using hot-spares), see "Features of Onboard RAID
Controller (MegaRAID ROMB)".
RAID Controller
HDD 1 HDD 2
(36 GB) (36 GB)
RAID Controller
VD0-2
20GB
VD1-2
16 GB
HDD 2
(36 GB)
Disk Group 0: 108 GB
HDD 3
(36 GB)
VD0 (RAID5)
VD0-3
40 GB
20GB
VD1-3
VD1 (RAID5)
16 GB
32 GB
HDD 3
(36 GB)
4-36
DG0 108 GB