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
MJ702GL3-Y /
MJ702GL3-R
MJ704GL3-Y /
MJ704GL3-R
MJ708GL3-Y /
MJ708GL3-R
MJ716GL3-Y /
MJ716GL3-R
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
Hitachi Compute Rack 210H User's Guide
Memory capacity
2048 MB
4096 MB
8192 MB
16384 MB
System Unit Functions
Number of rank
1
1
2
2
3-21