Sun Microsystems Enterprise 250 Owner's Manual page 59

In addition to providing ECC protection for data, the system offers parity protection
on all system address buses. Parity protection is also used on the PCI and SCSI
buses, and in the UltraSPARC CPU's internal and external cache.
Status LEDs
The system provides easily accessible light-emitting diode (LED) indicators on the
system front panel, internal disk bays, and power supplies to provide a visual
indication of system and component status. Status LEDs eliminate guesswork and
simplify problem diagnosis for enhanced serviceability.
Status and control panel LEDs are described in "About the Status and Control
Panel" on page 8. Disk drive and power supply LEDs are described in "Error
Indications" on page 242.
Hot-Pluggable Disk Drives
The "hot-plug" feature of the system's internal disk drives permits the removal and
installation of drives while the system is operational. All drives are easily accessed
from the front of the system. Hot-plug technology significantly increases the
system's serviceability and availability, by providing the ability to:
Increase storage capacity dynamically to handle larger work loads and improve
system performance.
Replace disk drives without service disruption.
For more information about hot-pluggable disk drives, see "About Internal Disk
Drives" on page 54 and "About Disk Array Configurations and Concepts" on
page 189.
Support for RAID 0, RAID 1, and RAID 5 Disk
Configurations
The Solstice DiskSuite software designed for use with the system provides the ability
to configure system disk storage in a variety of different RAID levels. You choose the
appropriate RAID configuration based on the price, performance, and reliability/
availability goals for your system.
RAID 0 (striping), RAID 1 (mirroring), RAID 0+1 (striping plus mirroring) and
RAID 5 configurations (striping with interleaved parity) can all be implemented
using Solstice DiskSuite. You can also configure one or more drives to serve as "hot
spares" to fill in automatically for a defective drive in the event of a disk failure.
Chapter 4 Hardware Configuration 41