8456ch_Configflow.fm Draft Document for Review December 5, 2019 4:33 pm 10.6 General storage configuration guidelines Observe the following general guidelines when storage is configured in the DS8000:  GLYPH<SM590000> To achieve a well-balanced load distribution, use at least two extent pools (also known as  a  pool pair ), each assigned to a different internal server. If CKD and FB volumes are  required on the same storage system, configure at least four extent pools: Two for FB and  two for CKD. GLYPH<SM590000> The volume type for the first volume that is created in an address group is either FB or  CKD. That volume type determines the type for all other volumes (FB or CKD) in the entire  address group. A volume is one of 256 in a logical subsystem (LSS) or Logical Control  Unit (LCU). An LSS is one of 16 in an address group (except address group F, which has  only 15 LSSs). For more information about logical subsystems and address groups, see  4.4.5, “Logical subsystems” on page 122. GLYPH<SM590000> Volumes of one LCU/LSS can be allocated on multiple extent pools in the same rank  group. GLYPH<SM590000> Assign multiple ranks to extent pools to take advantage of storage pool striping.  Additionally, assign ranks from multiple device adapter (DA) pairs to an extent pool to  spread the workload and increase performance. See 6.5.2, “Data placement in the  DS8000” on page 166. GLYPH<SM590000> The following options are available for fixed-block (FB) pools: – Create a volume group for each server unless logical unit number (LUN) sharing is  required. – Assign the volume group for one server to all of its host connections. – If LUN sharing is required, the following steps provide two possible use cases  (Figure 10-1): GLYPH<129> Application sharing - Create one volume group for each server. Assign the shared  volumes in each volume group. Assign the individual volume groups to the  corresponding server’s host connections. The advantage of this option is that you  can assign private and shared volumes to each host.  GLYPH<129> Clustering - Create one common volume group for all servers. Place the shared  volumes in the volume group and assign the volume group to the host connections. Figure 10-1 LUN configuration for shared access 260  IBM DS8900F Architecture and Implementation