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## 12.4 DS8880 storage configuration for the CKD volumes 

This list contains the steps to configure CKD storage in the DS8880: 

1. Create the arrays. 

2. Create the CKD ranks. 

3. Create the CKD extent pools. 

4. Create the LCUs. 

5. Create the CKD volumes. 

You do not need to create volume groups or host connects for CKD volumes. If I/O ports in FICON mode exist, access to CKD volumes by FICON hosts is granted automatically, following the specifications in the input/output definition file (IODF). 

## 12.4.1 Creating the arrays 

Array creation for CKD volumes is the same as for FB volumes. For more information, see 12.3.2, “Creating the arrays” on page 401. 

## 12.4.2 Creating the ranks and extent pools 

When ranks and extent pools are created, you must specify -stgtype ckd . Then you can create the extent pool as shown in Example 12-57. 

dscli> mkrank -array A0 -stgtype ckd CMUC00007I mkrank: Rank R0 successfully created. dscli> lsrank ID Group State datastate Array RAIDtype extpoolID stgtype ============================================================== R0 - Unassigned Normal A0 6 - ckd dscli>  mkextpool -rankgrp 0 -stgtype ckd CKD_High_0 CMUC00000I mkextpool: Extent Pool P0 successfully created. dscli> chrank -extpool P0 R0 CMUC00008I chrank: Rank R0 successfully modified. dscli> lsextpool Name ID stgtype rankgrp status availstor (2^30B) %allocated available reserved numvol =========================================================================================== CKD_High_0 0 ckd 0 below 252 0 287 0 0 

When defining a rank, you can also specify the extent size. Starting with DS8880 R8.1 firmware, you can have ranks and extent pools with large 1113 cylinder CKD extents, or small 21 cylinder CKD extents. The extent unit is specified with the -extsize  parameter of the mkrank  command. The first rank added to an extent pool determines the extent size of the extent pool. Example 12-58 shows ranks with different extent sizes. 

dscli> lsrank -l ... 

<img src='content_image/978754.jpg'>

