Adding virtual disk units to an AIX logical partition

You can dynamically add virtual disk units to an AIX® logical partition that uses IBM® i resources. This allows you to increase the storage capacity of your AIX logical partition when needed.

About this task

Virtual disks simplify hardware configuration on the server because they do not require you to add additional physical devices to the server in order to run AIX. You can allocate up to 64 virtual disks to an AIX logical partition. Each virtual disk supports up to 1000 GB of storage. Each virtual disk appears to AIX as one actual disk unit. However, the associated space in the IBM i integrated file system is distributed across the disks that belong to the IBM i logical partition. Distributing storage across the disks provides the benefits of device parity protection through IBM i. Therefore, you do not have to use additional processing resources and memory resources by setting up device parity protection through AIX.

IBM i provides the ability to dynamically add virtual disks to an AIX logical partition. You can allocate disk space in the integrated file system and make it available to AIX without restarting the server or logical partition. The AIX administrator can also configure the newly allocated disk space and make it available without restarting the server.

To add virtual disks dynamically to an AIX logical partition, complete the following steps:

Procedure

If you use IBM Navigator for i, create a network-server storage space using IBM Navigator for i.
1. Expand My Connections > your server > Network > Windows Administration .
2. Right-click the Disk Drives and select New Disk.
3. In the Disk drive name field, specify the name that you want to give to the network-server storage space.
4. In the Description field, specify a meaningful description for the network-server storage space.
5. In the Capacity field, specify the size of the new network-server storage space in megabytes.
  To help you determine the size you want to use, see Installing AIX.
6. Click OK.
7. Continue with step 3.
If you use a character-based interface, create a network-server storage space using the character-based interface:
1. At an IBM i command line, type the command CRTNWSSTG and press F4.
  The Create NWS Storage Space (CRTNWSSTG) display opens.
2. In the Network-server storage space field, specify the name you want to give to the network-server storage space.
3. In the Size field, specify the size in megabytes for the new network-server storage space.
  To help you determine the size you want to use, see Installing AIX.
4. In the Text description field, specify a meaningful description for the network-server storage space.
5. Press Enter.
6. Continue with step 4
If you use IBM Navigator for i, link the network-server storage space using IBM Navigator for i.
1. Expand My Connections > your server > Network > Windows Administration .
2. Click Disk Drives, right-click an available network-server storage space, and select Add Link.
3. Select the server to which you want to link the network-server storage space.
4. Select one of the available data access types.
5. Click OK.
6. Continue with step 5.
If you use a character-based interface, link the network-server storage space using a character-based interface:
1. At an IBM i command line, type the command ADDNWSSTGL and press F4.
  The Add Network-Server Storage Link (ADDNWSSTGL) display opens.
2. In the Network server description field, specify the name of the network server description (NWSD).
3. In the Dynamic storage link field, specify *YES to make the network-server storage space dynamically available to the logical partition (that is, available without rebooting the AIX logical partition).
4. In the Drive sequence number field, specify the link sequence position you want to use.
5. Press Enter.
Activate the AIX logical partition (if it is not already activated).
Log in to AIX using a user name with superuser (root) privileges.
Configure the new virtual disk on the AIX logical partition by running the AIX command cfgmgr.
Verify that your new disk has been added and can be configured by running the AIX command lspv.
When you enter lspv at the command prompt, the system lists the disks that are currently available to AIX.
An example of the output for this command is below:
```
# lspv
hdisk0          00cad6aceafe8fe4                    rootvg          active
hdisk1          none                                None
```
Note the name of the new disk as it displays in the left-hand column.
Configure the new disk using one of the following two methods.
- Add the new virtual disk to the root volume group by using the AIX command extendvg rootvg diskname, where diskname is the name of the new disk. If you use this method, you do not need to continue this procedure. You can use AIX methods to increase the file system size at a later time.
- Create a new volume group for the new virtual disk by using the AIX command mkvg -y volgroup diskname, where volgroup is the name that you want to use for the new volume group and diskname is the name of the new disk.
Make a logical volume on the new virtual disk using the AIX mklv -y logicvol volgroup 1 diskname command.
logicvol is the name that you want to use for the new logical volume, volgroup is the name of the new volume group, and diskname is the name of the new disk. (The numeral 1 indicates that the logical volume is to consist of one logical disk partition.)
Format the disk partition using the AIX crfs command.
There are a number of optional parameters for the crfs command, but typically the defaults satisfy most disk uses. To format the disk partition created in the previous steps, type the following command at an AIX command prompt, where logicvol is the name of the logical volume and /mnt/data is the mount point directory at which you want to mount the new disk:
```
 crfs -v jfs -d logicvol -m /mnt/data
```
The crfs command displays the following diagnostic messages:
```
crfs -v jfs -d logicvol -m /mnt/data
Based on the parameters chosen, the new /mnt/data JFS file system is limited to 
a maximum size of 134217728 (512 byte blocks)
New File System size is 8192.
```
Verify that the mount point directory exists by using the cd /mnt/data command.
/mnt/data is the mount point. The crfs command creates this directory so that you can access your new file system. If the mount point directory does not exist, then run the following command, where /mnt/data is the name of the mount point directory:
```
mkdir /mnt/data
```
Verify that an entry for your new file system exists in the /etc/filesystems file.
The crfs command automatically generates the appropriate /etc/filesystems entry for your new file system. To verify that the entry exists, use an AIX text editor, such as vi, to open the /etc/filesystems file, and look for the entry in the /etc/filesystems file. If the entry does not exist, use the text editor to add the entry to the /etc/filesystems file.
An example of such an entry is below:
```
/mnt/data:
	dev = /dev/logicvol
	vfs = jfs
	log = /dev/loglv01
	mount = true
	account = false
```
This entry mounts the virtual disk every time you restart AIX.
Mount the virtual disk drive in the new directory by typing: mount /dev/logicvol /mnt/data.
logicvol is the name of the logical volume and /mnt/data is the mount point directory.