User`s guide

4-18
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.
HDD 1
(36 GB)
HDD 2
(36 GB)
HDD 3
(36 GB)
RAID Controller
DG0 108 GB
VD1-3
16 GB
VD1-2
16 GB
VD1-1
16 GB
VD0-1
20GB
VD0-2
20GB
VD0-3
20GB
VD0 (RAID5)
40 GB
VD1 (RAID5)
32 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.