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System Overview 1-23
Disk Array
The optional disk array controller board is a PCI board that improves data reliability.
The disk array controller board allows the hard disk drives in the SCSI hard disk drive
bays and additional optional disk expansion unit to support disk array configuration
RAID levels 0, 1, and 5.
RAID is an acronym of “Redundant Arrays of Inexpensive (Independent) Disks”. It
logically integrates several hard disks to appear to the system as only one disk drive.
Using the disk array method, the large-capacity hard disk can be configured with
several inexpensive and small-capacity hard disks. It can also enhance the drive by
improving the reliability and supporting an automatic rebuilding function.
All RAID levels are common in their basic operation due the fact that several hard disks
can be recognized as one disk drive. However, performance, cost, and use are
conditions that vary according to the RAID level. You should select an appropriate
configuration that is suitable for your system.
Features and selection examples of different RAID levels are shown below.
Level
Definition
Redund-
ancy
Feature
Suitable
application
Minimum
No. of disks
RAID0
Striping
No
Access: high-speed.
Application that
needs high
performance for
non-critical data
2
RAID1
Mirroring
(or shadowing)
Yes
Dual disk system.
Read mode: high-
speed
Write mode: slower
than RAID 0
Application that
needs to store
important files
on main system
drive
2
RAID5
Striped data
and parity
Yes
Parity data.
Transfers large
amount of data.
Write mode: slower
than RAID 0
Application that
needs to store
important data.
Application of
read-intensive
type
data searching.
3
This unit supports other RAID levels as well. However, it is not recommended to use
them unless absolutely necessary.
Summary of Contents for EXPRESS5800/120Md Series
Page 1: ... U s e r s G u i d e EXPRESS5800 120Md ...
Page 2: ...NEC ...
Page 3: ... U s e r s G u i d e EXPRESS5800 120Md ...
Page 58: ...2 16 Setting Up the System Figure 2 10 Connecting the AC Power Cord to the Server ...
Page 64: ...2 22 Setting Up the System ...
Page 92: ...3 28 Configuring Your System ...
Page 165: ...A Technical Specifications Server Unit ...
Page 168: ...A 4 Technical Specifications ...
Page 174: ...B 6 Interrupt Request PCI IRQ Device I O Port Address Assignments ...
Page 185: ...D ROMPilot BIOS Error Codes ROMPilot BIOS Error Codes ...
Page 188: ...D 4 ROMPilot BIOS Error Codes ...
Page 198: ...10 Glossary ...
Page 204: ...Index 4 ...
Page 205: ...xx ...
Page 206: ... 456 01557 N00 ...