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## 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. 

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