Raid Configuration; Selecting Raid Level - NEC Express5800 User Manual

4-28 Configuring Your Server

RAID CONFIGURATION

This section describes how to configure the internal hard disk drives as the disk array drive by using
the onboard RAID controller (LSI Logic Embedded MegaRAID). Refer to the manual of the
optional disk array controller for how to configure the hard disk drives by using the optional disk
array controller.

Selecting RAID Level

You can configure a disk array (RAID0 or RAID1) by using the onboard RAID controller of the
server. Two SCSI hard disk drives are required to configure a disk array.
RAID0 (striping)
Stores data onto two hard disk drives by dividing it. This method is called "striping". This
improves disk access performance compared with using a single hard disk drive.
IMPORTANT:
RAID0 does not have data redundancy. When a hard disk drive
failure occurs, data cannot be restored.
Logical capacity of the array becomes a multiple of the connected
hard disk drive.
RAID1 (mirroring)
Stores the data being saved to one hard disk dive to another hard disk drive. This method
is called "mirroring". When storing data onto one hard disk drive, the same data is
simultaneously stored onto another hard disk drive. When a hard disk drive becomes
faulty, the one with the same data can be used. This provides operation without the system
going down.
IMPORTANT:
RAID1 reads or writes data to/from two hard disk drives at the same
time. The disk access performance is lower than the single disk.
Logical capacity of the array is equal to one hard disk drive
connected.