HP proliant ML110 Operation And Maintenance Manual page 44

VSC occurs when both channels are populated but the DIMMs are not identical or there
is an odd number of identical DIMMs. The MCH behaves identical in both single-
channel and virtual single-channel modes (hereafter referred to as single-channel (SC)
mode).
In SC mode of operation, the populated DIMMs configuration can be identical or
completely different. In addition, for SC mode, not all the slots need to be populated. For
example, populating only one DIMM in channel A is a valid configuration for SC mode.
Likewise, in VSC mode odd number of slots can be populated. For Dynamic Mode
operation, the requirement is to have an even number or rows (side of the DIMM)
populated. In SC, dynamic mode operation can be enabled with one single-sided (SS),
two SS or two double-sided (DS). For VSC mode, both the channels need to have
identical row structures.
•
Dual-channel lock step mode (DS)
— DS linear mode
This mode is the normal mode of operation for the MCH.
•
Dynamic addressing mode
When the MCH is configured to operate in this mode, FSB-to-memory bus address
mapping undergoes a significant change compared to that of a linear operating mode
(normal operating mode). In non-dynamic mode, the row selection (row indicates the side
of a DIMM) via chip select signals is accomplished based on the size of the row. For
example, for a 512 MB, 16Mx8x4b has a row size of 512 MB selected by CS0# and only
four open pages can be maintained for the full 512 MB. This lowers the memory
performance (increases read latencies) if most of the memory cycles are targeted to that
single row, resulting in opening and closing of accessed pages in that row.
Dynamic addressing mode minimizes the overhead of opening/closing pages in memory
banks allowing for row switching to be done less often.
SC or DS modes can be enabled with/without dynamic addressing mode enabled.
Table 4-1 below summarizes the different memory controller operating modes.
Table 4-1: Memory Controller Operating Modes
Mode type
SC mode
DS mode
Note: (*) special cases – need to meet the requirements discussed in the "Dynamic addressing
mode" item above.
HP ProLiant ML110 Server Operations and Maintenance Guide
Channel A only
Channel B only
Both channel A and B
Dynamic addressing
mode
Yes *
Yes *
Yes *
Yes
System Configuration
Non-dynamic
addressing mode
Yes
Yes
Yes
Yes *
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