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4 PowerVM Migration from Physical to Virtual Storage
1.4 Storage device compatibility in a Virtual I/O Server
environment
Physical-to-virtual (p2v) device compatibility refers only to the data on the device,
not necessarily to the capabilities of the device. A device is p2v compatible when
the data retrieved from that device is identical regardless of whether it is
accessed directly through a physical attachment or virtually (for example, through
the Virtual I/O Server). That is, every logical block (for example, LBA 0 through
LBA n-1) returns identical data for both physical and virtual devices. Device
capacity must also be equal in order to claim p2v compliance. You can use the
Virtual I/O Server chkdev command to determine whether a device is p2v
compatible. The chkdev command is available in Virtual I/O Server Version 2.1.2
FP22 or later.
Virtual disk devices exported by the Virtual I/O Server are referred to as virtual
SCSI disks. A virtual SCSI disk device may be backed by an entire physical
volume, a logical volume, a multi-path device, or a file.
Data replication functions such as copy services and device movement between
physical and virtual environments are common operations in today's data center.
These operations, involving devices in a virtualized environment, often have a
dependency on p2v compliance.
Copy services refer to various solutions that provide data replication functions
including data migration, flashcopy, point-in-time copy, and remote mirror and
copy solutions. These capabilities are commonly used for disaster recovery,
cloning, backup/restore, and more.
Device migration from physical environments to client partitions refers to the
ability to migrate a physical storage device to a Virtual I/O Server client partition
without the need for a backup and restore operation. The storage device may be
a direct-attached SCSI or SAN disk or tape device. This capability is very useful
for server consolidation.
The operations above may work if the device is p2v compatible. However, not all
device combinations and data replication solutions have been tested by IBM. See
claims by your copy services vendor for support claims for devices managed by a
Virtual I/O Server. See also PowerVM and SAN Copy Services, REDP-4610
(available 1Q, 2010).