User guide

Compaq StorageWorks RAID Array 4000 User Guide
Drive array technology distributes data across a series of hard drives to unite
these physical drives into one or more higher performance logical drives.
Distributing the data makes it possible to access it concurrently from multiple
drives in the array, yielding faster I/O rates than nonarrayed drives. Each
logical drive in the array can be set to a different fault-tolerant configuration.
The RA4000 Controller manages the drive array independent of the host
processor.
There are several ways to configure each set of hardware. The Array
Configuration Utility is used to help you configure the hardware in the way
that best suits your needs. For more information on storage expansion, see
Appendix E, “Hard Drive Arrays.” See Chapter 6, “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:
n Distributed data guarding (RAID 5)
n Data guarding (RAID 4)
n Drive mirroring (RAID 1)
n 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 the fault
tolerance settings, see Appendix E, “Hard Drive Arrays.”