Fault Tolerance; Capacity Expansion - Compaq RAID Array 4100 User Manual

1-8 Compaq StorageWorks RAID Array 4100 User Guide

Fault Tolerance

Capacity Expansion

There are several ways to configure each set of hardware. The Array
Configuration Utility helps you configure the hardware in the way that best
suits your needs. See Chapter 5, "Running the Array Configuration Utility,"
for information on the Array Configuration Utility.
Fault tolerance refers to several possible methods used to protect your system
from data loss in the event of a hardware failure somewhere in the storage
system. Each method has its advantages; choosing one requires careful
planning for your particular requirements.
The fault-tolerance methods supported by the RA4000 Controller and the
Compaq Array Configuration Utility include:
I
Distributed data guarding (RAID 5)
I
Data guarding (RAID 4)
I
Drive mirroring (RAID 1)
I
No fault tolerance (RAID 0)
Further data protection can be achieved by assigning an online spare to any
RAID 1, RAID 4, or RAID 5 configuration. For more information on fault
tolerance settings, see Appendix E, "Hard Drive Arrays."
Capacity Expansion refers to the ability to add storage capacity to an existing
array by adding hard drives.
The Array Configuration Utility lets you perform Capacity Expansion, even in
fault-tolerant configurations, without requiring a data backup and restore
cycle. If you are using Microsoft Windows NT or Novell NetWare operating
systems, the storage expansion can also be performed online, without leaving
the server operating system. For more information on storage expansion, see
Appendix E, "Hard Drive Arrays."