System
Unit
Functions
3-21
Hitachi Compute Rack 210H User’s Guide
Online spare memory is set for each channel. One rank of the memory board
installed on each channel becomes spare memory, and the other memory board
rank becomes system memory. A "rank" represents a memory board
configuration. Memory boards include a "single rank" and a "dual rank". Each
memory board operates on a "rank" basis. Therefore, the "dual rank" is
physically a single board but logically operates as two memory boards.
The number of the ranks of the memory board which a system unit supports is as
follows.
Table 3-1: The number of the ranks of the memory board
Product code
Memory capacity
Number of rank
MJ702GL3-Y /
MJ702GL3-R
2048 MB
1
MJ704GL3-Y /
MJ704GL3-R
4096 MB
1
MJ708GL3-Y /
MJ708GL3-R
8192 MB
2
MJ716GL3-Y /
MJ716GL3-R
16384 MB
2
In case the of a memory error, memory switching is performed on a rank basis.
For instance, on the assumption that a memory board having two rank is
installed on memory slots 1 and 5 (channel 1) of processor 1, and a memory
board of rank 0 in memory slot 1 is set as a spare memory.
If a correctable error occurs frequently on memory board of rank 0 in memory
slot 5, all data in the memory is copied online to memory board of rank 0 in
memory slot 1 which is spare memory. After the completion of copying, the
system unit starts operating by using the memory boards not including the
memory board of rank 0 in memory slot 5.
Figure 3-16: Operation of the online spare memory function
