IBM 9009-41A Manual page 73

Figure 53. Reconnecting the SAS cable in the 12-drive expanded function configuration
For information about SAS cable part numbers, see 9009-41A, 9009-41G, 9009-42A, 9009-42G, or
9223-42H system parts (http://www.ibm.com/support/knowledgecenter/POWER9/p9ecs/
p9ecs_914_924_parts.htm).
6. Fully seat all the front drives and front fillers if present into their slots as shown in the following figure.
Push drive lever (A) until the front drive and filler is seated and the lever snaps closed.
Drive backplanes for the 9009-41A, 9009-41G, 9009-42A, 9009-42G, or 9223-42H 59