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4.0 H
ARDWARE
4.1
Recommended Configuration
1.
Strongly recommended: Attach equal number of Ultrastar memory devices
between the sockets (consult your system manual for PCIe-to-socket mapping).
Less than one Ultrastar memory device per socket will result in inferior
performance.
2. Multiple Ultrastar memory devices can be installed and are aggregated to
improve performance; optimize for the highest aggregated 4K IOPS across all
Ultrastar memory devices.
3. A smaller capacity Ultrastar memory drive for each processor/socket will yield
better performance than a single larger capacity device attached to only one of
multiple sockets. For example, in a dual socket system, two Ultrastar memory
devices with capacity of 1TiB, attached one to each socket, would perform better
than a single 2TiB Ultrastar memory device attached to only one of the sockets.
The same holds true for multiple devices per socket: Two smaller capacity
Ultrastar memory devices per each processor/socket will yield better
performance than a single larger capacity device attached to each socket. For
example, in a dual socket system, four Ultrastar memory devices with capacity of
1TiB attached two to each socket, would perform better than a two 2TiB Ultrastar
memory device attached one to each socket.
4.2
DRAM to Ultrastar Memory Drive Ratio
Ultrastar memory drive uses part of the overall capacity (DRAM + NVM) for caching,
prefetching, and endurance protection. Thus, adding capacity in either DRAM or
Ultrastar memory drives may result in lower increase or no increase at all in the
system memory available for the OS. This can be overridden by changing Ultrastar
memory drive system memory settings at boot time (<F5>, system settings) from
Automatic to Manual.
For example, when set to Automatic, with 512GiB of DRAM on a system with four
1024GiB Ultrastar memory devices, an increase in number of drives to six will result in
improved performance. However, the system memory available for the OS will not be
increased (it will remain 4TiB).
Tables 4-1 and 4-2 indicate the total SDM capacity for a specific DRAM and Ultrastar
memory drive configurations, optimized for performance. Using a higher number of
devices for the same total capacity increases performance. Actual system memory
capacity may vary by ±3% compared to the tables below. Some valid, but less
frequent, configurations are not listed. For example, it is allowed to have a quad-
socket system with less than 2TiB system memory, or an octa-socket system with less
than 8TiB system memory.
Hardware Configuration
C
ONFIGURATION
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