Reliability, Availability, And Serviceability - Acer HDS AMS200 Reference Manual

1.1.5

Reliability, Availability, and Serviceability

The AMS200 subsystem is not expected to fail in any way that would interrupt user access to
data. The AMS200 can sustain single component failures and still continue to provide full
access to all stored user data.
Note: While access to user data will not normally be compromised, the failure of any single
key component may degrade performance.
The reliability, availability, and serviceability features of the AMS200 subsystem include:
High-Availability capability. The AMS200 subsystem provides high-availability capability
for all critical components. The AMS200 uses component and function redundancy to
provide high availability for many subsystem components.
The Controller of the AMS200 subsystem increases data reliability by adding original 8-
byte data assurance codes to data from a host computer by automatically generating
them, writing them in the disk drive together with the data, and checking them when
reading the data. On the data bus in the controller, the automatic generation of the
data assurance codes and the check are executed to enhance data reliability in data
distribution/concentration control, particular to that disk array.
This function monitors potential disk failure. Before failure occurs, the data copy
operation can be automatically performed in the background. The dynamic sparing
feature enables the subsystem to replace the spare disk due to redundancy (excluding
RAID0 configuration) and provides high reliability.
Redundant power supply systems. Each AMS200 unit has a set of two power supplies.
Each power supply can provide power for the entire subsystem in the unlikely event of
power supply failure. The power supplies of each set can be connected across power
boundaries so that each set can continue to provide power if a power outage occurs.
Each unit of the AMS200 can sustain the loss of a single power supply and still continue
operation.
High capacity cache. The AMS200 subsystem supports 2 GBs high capacity cache per
controller. Writing completion can be reported to the host system when data is written
to cache.
4 Chapter 1 Overview of the AMS200 Subsystem