Creating a volume group for System i systems

Complete this task to create volume groups for System i systems so that volumes can be assigned to the i5 fibre-channel adapters.

Use the mkvolgrp command to create a volume group that contains the volumes to be assigned to an i5 fibre-channel adapter. The following considerations determine how you will create your volume groups:

If you are using a multipath connection, a volume group is assigned to two or more i5 fibre-channel adapters. Each fibre-channel adapter provides one path to volumes in the volume group.
If you are using an external load source, you create a volume group that contains one volume. After a partition is initially loaded from the external load source, you can add more volumes to this volume group so that the i5/OS recognizes them and can use them.
If you do not use an external load source, you create a volume group that contains all the volumes that are assigned to an i5 fibre-channel adapter. You cannot specify more than 32 LUN volumes for each attachment to an i5 fibre-channel adapter.

When you create a volume group for i5/OS, you should specify the -hosttype iSeries parameter as part of the mkvolgrp command. The -hosttype iSeries parameter saves some processing time because this parameter automatically supplies information that would have to be specified separately.For example, the i5/OS uses a logical blocksize of 520, and volumes that are created for i5/OS use a blocksize of 520 bytes. By specifying the -hosttype iSeries parameter,also you denote that the logical size of the blocks in the volumes is 520 bytes.

Perform the following steps to create and view volume groups for System i systems:

Issue the mkvolgrp command to create a volume group. Enter the mkvolgrp command at the dscli command prompt with the following parameters and variables:
Note: Repeat this step for each volume group that you want to create.

The following two examples provide the commands that you can use to create volume groups depending on whether you use the external load source. The first example creates a volume group that contains one unprotected volume if you do use an external load source. (If you are using an external load source, you can initially only have one volume in the volume group.) The second example creates a volume group that contains all volumes if you do not use an external load source.
Example 1 (using an external load source)
```
dscli>mkvolgrp  -dev IBM.1750-13ABVDA -hosttype iSeries -volume 1000 blue

Date/Time: July 5, 2005 11:57:50 PM GMT+01:00 IBM DSCLI Version: 5.0.4.32
DS: IBM.1750-13ABVDA 
CMUC00030I mkvolgrp: Volume group V14 successfully created.
```
Example 2 (not using an external load source)
```
dscli>mkvolgrp  -dev IBM.1750-13ABVDA -hosttype iSeries -volume 1000-1002 blue

Date/Time: July 5, 2005 11:57:50 PM GMT+01:00 IBM DSCLI Version: 5.0.4.32
DS: IBM.1750-13ABVDA 
CMUC00030I mkvolgrp: Volume group V14 successfully created.
```
Notes:
1. The confirmation message for the end process shows that the created volume group is automatically assigned an ID that is different from the name of the volume group that you specify in the command. You will see the name that you assigned associated with the volume group when you use the lsvolgrp and showvolgrp commands. However, if you want to work specifically with the volume group, you must reference the volume group ID.
2. This volume group is also referred to as SCSI520-MASK. When an error message is displayed for the OS400 MASK, SCSI520-MASK is referenced instead.
3. If you do not use an external load source, it is a good practice to create a volume group that contains all the volumes that will be assigned to the i5 fibre-channel adapter.
4. System i only supports 32 device addresses per volume group.
Issue the lsvolgrp command to create a list of assigned volume group IDs. Enter the lsvolgrp command at the dscli command prompt with the following parameters and variables:
```
dscli>lsvolgrp -dev IBM.1750-13ABVDA -l
```
Notes:
1. The lsvolgrp command with the -l parameter displays a report with the following three values:
  - Name (the unique name that you assigned to the volume group)
  - Volume group ID (the identification number of the volume group)
  - Type (the configured volume group type)
2. You can narrow the scope of the report by requesting a specific type of volume. See the lsvolgrp command for information about the -type parameter.
Verify your host type information by issuing the lshosttype command using the following command format at the dscli command prompt:
```
dscli>lshosttype  -type os400mask
```
This command displays a report like the following:
Name Profile AddrDiscovery LBS

iSeries IBM iSeries - os400 reportlun 520

Note: You can obtain the same results if you use the -type os400all parameter.