Product manual

CDA 7 5630 Product Manual
5-4 77 A1 69UP Rev00
5.2 Reliability and Availability Features
CDA 7 has several features that allow it to maintain data integrity and maximize
system availability. This section discusses several features in detail.
5.2.1 Reliable Components
CDA 7 uses components that have a mean time between failure (MTBF) of several
hundred thousand to millions of hours for a minimal component failure rate. A
redundant design allows CDA 7 to remain online and operational during
component repair.
A periodic system check tests all components as well as microcode integrity.
CDA 7 reports errors and environmental conditions to the host system as well as
the Bull Competence Center.
5.2.2 Redundant Power Subsystem
The CDA 7 has a modular power subsystem featuring a redundant architecture that
facilitates field replacement of any of its components without any interruption in
processing.
The CDA 7 power subsystem connects to two dedicated or isolated AC power
lines. If AC power fails on one AC line, the power subsystem automatically
switches to the other AC line.
The two power supplies operate in a redundant parallel configuration. If a power
supply module fails, the remaining power supply continue to share the load. CDA 7
senses the fault and reports it as an environmental error (error code 0472).
5.2.3 System Battery Backup
The entire CDA 7 system is made nonvolatile via an onboard battery backup
system. The battery backup system provides the means for destaging any fast write
data that might be in cache if AC power is lost on both AC power lines to the unit.
In addition to providing nonvolatility to the CDA 7 system, the batteries are fully
capable of powering not only all electronic components, but also all HDAs during
this time. This eliminates emergency power off situations, meaning that the disks
are always powered down in an orderly manner, which extends their useful life
considerably.