Cisco UCS C480 M5 Manual - Página 10

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Cisco UCS C480 M5 Manual

DIMM Memory Mirroring

DIMM Memory Mirroring
Memory mirroring is supported only on the DIMMs; DCPMMs do not support memory mirroring. When memory
mirroring is enabled, the memory subsystem simultaneously writes identical data to two adjacent channels.
If a memory read from one of the channels returns incorrect data due to an uncorrectable memory error,
the system automatically retrieves the data from the other channel. A transient or soft error in one channel
does not affect the mirrored data, and operation continues unless there is a simultaneous error in exactly
the same location on a DIMM and its mirrored DIMM. Memory mirroring reduces the amount of memory
available to the operating system by 50% because only one of the two populated channels provides data.
CPU/Memory Configuration With Memory Mirroring
There are two CPU modules, one in each CPU bay. The lower CPU module occupies Bay 1 and the upper CPU
module occupies Bay 2. CPU 1 and CPU2 are in Bay 1; CPU 3 and 4 are in Bay 2.
Select from 4, 6, 8, or 12 DIMMs per CPU (DIMMs for all four CPUs must be configured identically). In
addition, the memory mirroring option (N01-MMIRROR) as shown in
The DIMMs will be placed by the factory as shown in the following tables.
CPU 1 DIMM Placement in Channels
(for identical ranked DIMMs)
CPU 1
8
(A1,B1); (D1,E1)
12
(A1, B1, C1); (D1, E1, F1)
16
(A1, A2, B1, B2); (D1, D2, E1, E2)
24
(A1, A2, B1, B2, C1, C2); (D1, D2, E1, E2,
F1, F2)
CPU 3 DIMM Placement in Channels
(for identical ranked DIMMs)
CPU 3
8
(A1,B1); (D1,E1)
12
(A1, B1, C1); (D1, E1, F1)
16
(A1, A2, B1, B2); (D1, D2, E1, E2)
24
(A1, A2, B1, B2, C1, C2); (D1, D2, E1, E2,
F1, F2)
10
NOTE: System performance is optimized when the DIMM type and quantity are equal
for both CPUs, and when all channels are filled equally across the CPUs in the server.
Table 1 on page 5
CPU 2 DIMM Placement in Channels
(for identical ranked DIMMs)
CPU 2
(G1, H1); (K1, L1)
(G1, H1, J1); (K1, L1, M1)
(G1, G2, H1, H2); (K1, K2, L1, L2)
(G1, G2, H1, H2, J1, J2); (K1, K2, L1, L2, M1,
M2)
CPU 4 DIMM Placement in Channels
(for identical ranked DIMMs)
CPU 4
(G1, H1); (K1, L1)
(G1, H1, J1); (K1, L1, M1)
(G1, G2, H1, H2); (K1, K2, L1, L2)
(G1, G2, H1, H2, J1, J2); (K1, K2, L1, L2, M1,
M2)
Cisco UCS C480 M5 Memory Guide
must be selected.