Memory Ras Functions; Memory Mirroring - NEC Express 5800 User Manual

Hardware

Memory RAS Functions

The server supports the following functions as RAS functions.
There are some restrictions for the mounted memory when using each function. Refer to each
section for details.
 Memory Mirroring Function
 DIMM Sparing Function
 Memory Scrubbing Function

Memory Mirroring

The Memory Mirroring function provides high fault tolerance similar to the memory RAID function.
Memory Mirroring is one of the RAS functions. This function prepares memory for mirroring that
has the same capacity (or more) for the memory whose contents are to be protected and
constantly duplicates (mirrors) the whole contents of the memory in the mirroring memory. In
case memory failure occurs, it can protect the contents stored in the memory by switching to the
mirroring memory.
Set Memory Mirroring from "Memory Mirroring" in Web Console.
There are two types of Memory Mirroring as below.
(1) Mirroring in the processor memory module
(2) Mirroring between processor memory modules
Each type is described in the next pages.
NOTE:
RAS is the abbreviation of Reliability, Availability, and
Serviceability. It is the concept of technological background to
improve reliability of systems. RAS consists of the initial letters of
these three basic technological concepts.
Reliability signifies to prevent a failure of hardware or software.
Mean time between failure, "MTBF," is used as an indicator.
Availability is the term for improvement of the system availability
and the importance of this term is how to recover from failure as
quickly as possible.
IMPORTANT:
● Memory Mirroring and DIMM Sparing cannot be set
simultaneously.
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