Sun Microsystems 220R manual About Reliability, Availability, and Serviceability Features

About Reliability, Availability, and Serviceability Features

Reliability, availability, and serviceability are three aspects of a system’s design contributing to continuous operation and minimizing system downtime for service. Reliability refers to a system’s ability to operate continuously without failures and to maintain data integrity. System availability refers to the percentage of time that a system remains accessible and usable. Serviceability relates to the time it takes to restore a system to service following a system failure. Together, reliability, availability, and serviceability provide for near continuous system operation.

To deliver high levels of reliability, availability, and serviceability, the system offers the following features:

■Error correction and parity checking for improved data integrity

■Easily accessible status indicators

■Hot-pluggable disk drives

■Support for RAID 0, 1 storage configurations on internal drives

■Support for RAID 0, 1, 0 +1, and 5 storage configurations on external disk drives

■Redundant power supply support

■Hot-swappable power supplies

■Four different levels of system diagnostics

Error Correction and Parity Checking

Error-correcting code (ECC) is used on all internal system data paths to ensure high levels of data integrity. All data that moves between processors, I/O, and memory have end-to-end ECC protection.

The system reports and logs correctable ECC errors. A correctable ECC error is any single-bit error in a 64-bit field. Such errors are corrected as soon as they are detected. The ECC implementation can also detect double-bit errors in the same 64-bit field and multiple-bit errors in the same nibble (4 bits).

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.

62 Sun Enterprise 220R Server Owner’s Guide • October 1999