Sun Microsystems Netra 1290, Руководство администратора

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Chapter 1 Netra 1290 Server Overview 5
Reliability, Availability, and
Serviceability (RAS)
Reliability, availability, and serviceability (RAS) are features of this system.
■
Reliability is the probability that a system stays operational for a specified time
period when operating under normal environmental conditions. Reliability differs
from availability in that reliability involves only system failure, whereas
availability depends on both failure and recovery.
■
Availability, also known as average availability, is the percentage of time that a
system is available to perform its functions correctly. Availability can be measured
at the system level or in the context of the availability of a service to an end client.
The system availability imposes an upper limit on the availability of any products
built on top of that system.
■
Serviceability measures the ease and effectiveness of maintenance and server
repair for the product. There is no single well-defined metric, because
serviceability can include both Mean Time to Repair (MTTR) and diagnosability.
The following sections provide details on RAS.
Reliability
The software reliability features include:
■
“Disabling Components or Boards and Power-On Self-Test (POST)” on page 5
■
“Manual Disabling of Components” on page 6
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“Environmental Monitoring” on page 6
The reliability features also improve system availability.
Disabling Components or Boards and Power-On Self-Test
(POST)
The power-on self-test (POST) is part of powering on the server. If the board or
component fails testing, POST disables components or boards. The
showboards
command displays the board as either being failed or degraded. The server, running
the Solaris Operating System, is booted only with components that have passed
POST testing.