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EMC Symmetrix DMX-3 Product Guide
Data Integrity, Availability, and Protection
Reliability and availability features
Symmetrix systems have several features that allow them to maintain
data integrity and maximize system availability. This section
discusses several features in detail.
Reliable
components
Symmetrix systems use 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
Symmetrix systems to remain online and operational during
component repair.
A periodic system check tests all components as well as microcode
integrity. Symmetrix systems report errors and environmental
conditions to the host system as well as the EMC Customer Support
Center.
Global memory
director data
integrity
Every Symmetrix system is configured with a minimum of two global
memory directors to allow for online nondisruptive replacement of a
failing global memory director. When a hard error is detected, or
temporary errors reach a predetermined threshold, the Symmetrix
service processor calls home to request an immediate maintenance
action.
Note: “Maintaining data integrity” on page 175 provides more information
on global memory director data integrity protection.
Redundant global
memory
Symmetrix DMX-3 global memory director operations are redundant
by way of a primary and secondary global memory director working
as a pair. If an error is detected in one of the memory directors, no
writes are allowed to the board containing the error. The writes will
be made to the nonfailing memory director until the failed global
memory director is replaced. The remaining good memory director
remains unprotected until a memory director replacement is
performed on the failed memory director. When the new memory
director is installed, Global Services personnel perform a copy back
from the good remaining director to the newly installed director. This
ensures that both memory directors are completely synchronized in
the Symmetrix DMX-3 system.
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