Virtual Disk - NEC Express5800 series User Manual

4-4
Configuring Your Storage and I/O Blade

Virtual Disk

Virtual disk is a logical drive defined in disk group. It is recognized as a physical drive by OS. The
allowable 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 Internal RAID Controller is connected
with 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
The parity means redundant data. A single set of redundant data is created from the data saved in
more than one HDD.
The created redundant data is used for data recovery when a HDD is defected.
Hot-Swap
The hot-swap 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 defected 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.
RAID Controller
VD0-2
20GB
VD1-2
16 GB
HDD 2
(36 GB)
DG0 108 GB
VD0 (RAID5)
VD0-3
40 GB
20GB
VD1-3
VD1 (RAID5)
16 GB
32 GB
HDD 3
(36 GB)