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Memory rank sparing mode

In rank-sparing mode, one memory DIMM rank serves as a spare of the other ranks on the same channel. The spare rank is held in reserve and is not used as active memory. The spare rank must have identical or larger memory capacity than all the other active DIMM ranks on the same channel. After an error threshold is surpassed, the contents of that rank is copied to the spare rank. The failed rank of DIMMs is taken offline, and the spare rank is put online and used as active memory in place of the failed rank.

There are two sections for memory sparing mode:

Section 1: Rank-sparing mode for single rank (1R) memory​

Table 1. DIMM population sequence for rank-sparing mode for single rank (1R) memory
Number of installed processorsNumber of installed DIMMsDIMM connector
125, 6
45, 6, 7, 8
65, 6, 7, 8, 3, 4
85, 6, 7, 8, 3, 4, 9, 10
105, 6, 7, 8, 3, 4, 9, 10, 1, 2
125, 6, 7, 8, 3, 4, 9, 10, 1, 2, 11, 12
245, 6, 20, 19
85, 6, 20, 19, 7, 8, 18, 17
125, 6, 20, 19, 7, 8, 18, 17, 3, 4, 22, 21
165, 6, 20, 19, 7, 8, 18, 17, 3, 4, 22, 21, 9, 10, 16, 15
205, 6, 20, 19, 7, 8, 18, 17, 3, 4, 22, 21, 9, 10, 16, 15, 1, 2, 24, 23
245, 6, 20, 19, 7, 8, 18, 17, 3, 4, 22, 21, 9, 10, 16, 15, 1, 2, 24, 23, 11, 12, 14, 13

Section 2: Rank-sparing mode for dual (2R) or higher rank memory​

Table 2. DIMM population sequence for rank-sparing mode for dual (2R) or higher rank memory with one processor
Number of installed DIMMs1 processor installed
DIMM connector
15
25, 8
35, 8, 3
45, 8, 3, 10
55, 8, 3, 10, 1
65, 8, 3, 10, 1, 12
73, 5, 8, 10, 12, 4, 6
83, 4, 5, 6, 8, 10, 7, 9
93, 4, 5, 6, 8, 10, 12, 1, 2
101, 2, 3, 4, 5, 6, 8, 10, 7, 9
111, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12
121, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 11
13Not used - maximum of 12 DIMMs in systems with 1 processor
Table 3. DIMM population sequence for rank-sparing mode for dual (2R) or higher rank memory with two processors
Number of installed DIMMs2 processors installed
DIMM connector
25, 20
45, 20, 8, 17
65, 8, 17, 20, 3, 22
83, 5, 8, 17, 20, 22, 10, 15
103, 5, 8, 10, 15, 17, 20, 22, 1, 24
121, 3, 5, 8, 10, 13, 15, 17, 20, 22, 12, 24
143, 5, 8, 10, 12, 13, 15, 17, 20, 22, 4, 6, 19, 21
163, 4, 5, 6, 8, 10, 15, 17, 19, 20, 21, 22, 7, 9, 16, 18
183, 4, 5, 6, 8, 10, 15, 17, 19, 20, 21, 22, 1, 2, 12, 13, 23, 24
201, 2, 3, 4, 5, 6, 8, 10, 15, 17, 19, 20, 21, 22, 23, 24, 7, 9, 16, 18
221, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 12, 13
241, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 11, 14