Creating count key data extent pools using the DS CLI

Complete this task to create CKD volume extent pools. This is the first step in configuring new count key data storage. You can use the DS CLI commands to create extent pools for CKD volumes.

Creating the extent pools before the arrays and ranks saves a processing step. When you create the new ranks, you can assign them to existing extent pools. Otherwise, you must modify each rank object to complete the extent pool ID assignment after the extent pools have been defined.

Each extent pool is defined with the rank group of 0 or 1 and a storage type of ckd. At a minimum, you must define one extent pool for each rank group and storage type combination. This means that you must make a minimum of two extent pools for a storage unit that contains CKD storage: one CKD extent pool per rank group.

Extent pools that are defined for rank group 0 or 1 are assigned an even- or odd-numbered extent pool ID, respectively. Even-numbered extent pools are managed by storage server ID 0. Odd-numbered extent pools are managed by storage server ID 1. Each rank group is assigned to one extent pool; therefore, storage server workload is affected by the rank assignments to even- and odd-numbered extent pool IDs. It is better to evenly distribute rank and extent pool allocations in order to keep the storage server workloads balanced.

Notes:

You can create more than the minimum number of extent pools. For example, you can define unique extent pools for each RAID type (5 or 10) that is configured in a storage image. Or, you can define and name extent pools according to the host system attachments that access the volumes that are created from extent pool extents.
You can have the same number of extent pools as ranks.

Use the lsextpool and mkextpool commands to create the CKD extent pools. You must be logged into the DS CLI application and connected to the storage unit that will be used for your zSeries host system.

To make your extent pools, perform the following steps:

Find defined CKD extent pools by issuing the lsextpool command to display a list of the existing CKD extent pools. Type the following command at the dscli command prompt:
dscli> lsextpool -dev IBM.1750-75FA120 -stgtype ckd
Analyze the extent pool listing for the following information.
- Does the minimum set of extent pools exist? There must be one extent pool for rank group 0 and one extent pool for rank group 1.
  Note: If this is the first time that the extent pools are created, the minimum number of extent pools does not already exist.
- Does each extent pool have a rank group that is assigned to it and are they balanced? If this is the first time, there will be no rank assignments.
- Are additional extent pools needed?
Make your extent pools by issuing the mkextpool command. (A minimum of two extent pools must be created. One for rank group 0 and one for rank group 1.)
Type the following command at the dscli command prompt:
```
dscli>mkextpool -dev IBM.1750-68FA120 –rankgrp 0 -stgtype ckd 
extent_pool_name
dscli>mkextpool -dev IBM.1750-68FA120 –rankgrp 1 -stgtype ckd 
extent_pool_name
```
The extent_pool_name parameter is required with the mkextpool command. The extent pool name is a unique name that you assign to each extent pool and it cannot be longer than 16 characters.
Make additional extent pools for each of the following conditions:
- Each RAID type (5 or 10)
- Each disk drive module (DDM) size
- Each CKD volume type (3380, 3390)
- Each logical control unit (LCU) address group
Press Enter. A successful process displays the following message:
Note: The unique name that you assigned to the extent pool does not display in the process message. However, when you issue the lsextpool command, the extent pool name is displayed.
```
Sun Aug 11 02:23:49 PST 2004 IBM DS CLI Version: 5.0.0.0 DS: IBM.1750-75FA120

Extent pool P1 successfully created.
```
Repeat Step 2 for each extent pool that you want to create. Try to evenly distribute rank and extent pool allocations in order to keep the storage server workloads balanced.
Verify the extent pool assignments by issuing the lsextpool command when you are done making the extent pools. Use the -l parameter to display a full report for the extent pools that are assigned to the storage unit. Type the following command at the dscli command prompt:
dscli> lsextpool –dev IBM.1750-75FA120 -l

You might want to print this report because this list is used later during the process of creating CKD volumes.