Memory ras – HP ProLiant BL680c G7 Server-Blade User Manual
Page 54
Hardware options installation 54
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The best performance is obtained when all installed processors are enabled for Hemisphere mode.
Hemisphere mode is optimum when four or eight DIMMs are installed per memory controller.
Hemisphere mode can be achieved with two or six DIMMs per memory controller, but this configuration
is not optimal for Hemisphere mode.
•
Maximum throughput is achieved when all DIMM slots are fully populated with the maximum number of
eight quad-rank DIMMs per memory controller.
•
Memory speed is a function of the processor QPI bus speed. Selecting a processor that supports a
higher QPI speed enables the memory to operate at a higher performance level:
o
Processors that support a QPI speed of 6.4 GT/s enable the memory to operate at 1066 MT/s, the
maximum memory speed supported by the Intel® Xeon® 7500 processor.
o
Processors that support a QPI speed of 5.8 GT/s operate memory at 978 MT/s.
o
Processors that support a QPI speed of 4.8 GT/s operate memory at 800 MHz.
o
Memory performance degrades less when going from 1066 MHz to 984 MHz than it does when
going from 978 MHz to 800 MHz.
Plan the memory configurations using identical DIMMs to achieve the memory size target, taking into account
that 32- and 64-DIMM count configurations result in the highest performance. Using a four-processor
configuration as an example, do the following:
•
If the initial memory target is 64 GB, populate each processor with eight 2-GB DIMMs for a total of 32
DIMMs. The maximum expansion target using 2-GB DIMMs is 128 GB with 64 DIMMs.
•
If the initial memory target is 128 GB, populate each processor with eight 4-GB DIMMs for a total of 16
DIMMs. The maximum expansion target using 4-GB DIMMs is 256 GB with 64 DIMMs.
•
If the initial memory target is 256 GB, populate each processor with eight 8-GB DIMMs for a total of 16
DIMMs. The maximum expansion target using 8-GB DIMMs is 512 GB with 64 DIMMs.
The maximum system memory capability is 1 TB with 64 x 16-GB DIMMs (16 DIMMs per processor) or 2 TB
with 64 x 32-GB DIMMs. 32-GB DIMMs are supported only on server blades that support Intel® Xeon® E7
family processors.
Memory RAS
The server supports the following AMP modes:
•
Advanced ECC memory mode provides the greatest memory capacity for a given DIMM size and
provides x4 and x8 SDDC. This mode is the default option for this server. For more information, see
"Advanced ECC memory population guidelines (on page
)."
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DDDC ready. The server blade will support this feature with a future planned firmware upgrade. DDDC
is supported only on server models that support the Intel Xeon E7 family processors. DDDC extends the
capability to withstand failures in two x4 DRAM devices. Systems supporting DDDC can fix both single-
and double-DRAM device memory hard errors. This feature greatly extends system up-time. For more
information, see "Double Device Data Correction (on page
)."
•
HP Memory Quarantine ready. The server blade will support this feature with a future planned firmware
upgrade. The operating system must support this mode. HP Memory Quarantine works with the
operating system to enable a server to recover from uncorrectable memory errors that would have
otherwise caused a system crash. For more information, see "HP Memory Quarantine (on page
)."