IBM x3690 X5 Service Manual page 304

This configuration consists of four 4x2.5-inch drive backplanes and requires
four SAS signal cables.
This configuration consists of one 8x2.5-inch drive backplane and two
4x2.5-inch drive backplanes and requires four SAS signal cables.
This configuration consists of two 4x2.5-inch drive backplanes and one
8x2.5-inch drive backplane and requires four SAS signal cables.
This configuration consists of two 8x2.5-inch drive backplanes and requires four
SAS signal cables.
This configuration consists of two 4x2.5-inch drive backplanes and one
8x1.8-inch drive backplane and requires four SAS signal cables.
0 1 2 3 4 5 6 7 16 17 18 19 20 21 22 23
Empty
This configuration consists of one 8x2.5-inch drive backplane and one
8x1.8-inch drive backplane and requires four SAS signal cables.
286
System x3690 X5 Types 7147, 7148, 7149, and 7192: Problem Determination and Service Guide