Product data

18 PowerVM Migration from Physical to Virtual Storage
2.3 Creating a virtual SCSI device
In a virtual SCSI storage environment, the Virtual I/O Server owns the physical
SCSI cards and disks. The disks are then configured as backing devices on the
Virtual I/O Server so that client partitions can access these backing storage
devices. Physical disks owned by the Virtual I/O Server can be assigned to client
partitions in several different ways:
򐂰 The entire disk may be presented to the client partition.
򐂰 The disk may be carved up into multiple logical volumes and each logical
volume can be presented to the client partition.
򐂰 Files can be created on the disks on the Virtual I/O Server and these files can
be presented to the client partition as file-backed storage.
Thus, virtual SCSI enables the sharing of both SCSI adapters and disks.
To make a physical disk, logical volume, or file-backed storage device available to
a client partition:
1. Create one or more virtual SCSI server adapters on the Virtual I/O Server.
Assign server adapter IDs and also specify the adapter IDs that will be used
on the client partition. For additional information see also:
– PowerVM Virtualization on IBM System p: Introduction and Configuration
Fourth Edition, SG24-7940
– IBM PowerVM Virtualization Managing and Monitoring, SG24-7590
2. Create virtual SCSI client adapters on the client partition. Specify the same
adapter IDs selected on the Virtual I/O Server.
3. Create the virtual target mappings on the Virtual I/O Server such that the
client is connected to the correct server-side resources.
Virtual SCSI server adapters appear as vhost virtual devices on the Virtual I/O
Server, as shown in the following command output:
$ lsdev -dev vhost*
name status description
vhost0 Available Virtual SCSI Server Adapter
In the same way that a physical SCSI adapter allows access to multiple disks, a
virtual SCSI host adapter allows many disks to be mapped to it. The following
command is an example of how to map a disk—hdisk6 to a virtual SCSI host
adapter vhost5:
$ mkvdev -vdev hdisk6 -vadapter vhost5
vtscsi2 Available