Disk Array Bios - Scsiselect/Hostraid; Raid (Redundant Array Of Independent Disks); Using Scsiselect Menu - NEC Express5800 series User Manual

DISK ARRAY BIOS - SCSISelect/HostRAID -

The HostRAID feature is intended to control the disk array in the SCSI controller installed in a CPU
blade. Using the SCSISelect utility, you can provide the Host RAID with several settings.
The SCSISelect utility is a BIOS setup utility stored in a chip on the CPU blade. If the settings on
the HostRAID are made valid, SCSISelect allows RAID arrays to be created and managed. This
chapter describes how to use SCSISelect to make the HostRAID and create a RAID array in the
system. Use the HostRAID to realize the fault-tolerant and event notification features of appropriate
levels.

RAID (Redundant Array of Independent Disks)

The RAID (Redundant Array of Independent Disks) enables data to be protected, data availability to
be increased greatly, and the system to have excellent performance and high capacity. The RAID
has the following features:
Unified array
Several hard disk drives are grouped. If the hard disk drives operate independently, the
host system recognizes the group as a single device.
Redundancy with fault-tolerant feature
If a fault occurs in a single drive, data will not be lost.
The HostRAID supports the following RAID levels.
RAID 0: Striping
More than one drive can read or write data in parallel. This configuration can have higher
performance than only a single drive but does not provide the fault-tolerant feature. The
RAID 0 array does not store redundant data. Accordingly, if a fault occurs in a disk
included in the array, all data will be lost.
RAID 1: Mirroring
Data is mirrored to have 100% redundancy. This provides the perfect fault-tolerant feature.
If a fault occurs in a disk, the data is still available. The load balancing improves the
reading performance. It is recommended to use disks of the same capacity. If disks of
different capacities are used, the actual data capacity of the array is the same as the lowest
one.

Using SCSISelect Menu

To select a SCSISelect menu option, move the cursor to the desired option by using cursor key ↑ or
↓ and press Enter. When an option is selected, another menu may appear. Pressing Esc allows the
just previous menu to be recovered.
Configuring Your Server 4-27