HP Integrity Virtual Machines Installation, Configuration, and Administration Version A.03.50

Figure 7-3 shows an example of a VM Host I/O stack as it applies to a single LUN:

Figure 7-3 Sub-LUN Storage Allocation Example

File File File File File File File File

2 2

Logical Volume Logical Volume Logical Volume Logical Volume

Whole Disk

The virtual machine is allocated a logical volume from the LUN for a Virtual LvDisk.

• The logical volume that has been allocated is marked 1.

• The parts of the disk that cannot be allocated are marked 2.

Those parts that are no longer available include the files that were on the logical volume and the

whole disk that makes up part of the volume group. If any of these parts are allocated for other

virtual devices, data corruption can occur on the Virtual LvDisk.

Those parts that are still available for reallocation include other logical volumes that are on the

disk,and files that are on those other logical volumes on the disk. These pieces can be allocated

without data corruption problems because they do not overlap with the Virtual LvDisk.

Beyond avoiding sub-LUN collisions, whole LUN collisions also need to be avoided. The same

storage resource, virtual or attached, cannot be specified more than once to the same virtual

machine. Under HP-UX 11.23, most storage device files are defined per path. Be careful not to

specify a given device twice. Figure 7-4 shows an example of two device files,

/dev/rdsk/c6t2d0 and /dev/rdsk/c11t2d0 pointing to the same physical disk. Once the

/dev/rdsk/c6t2d0 device file is specified for a Virtual Disk, the /dev/rdsk/c11t2d0 device

file is no longer available.

Figure 7-4 Bad Multipath Virtual Media Allocation

Physical

Adapter

Physical

Adapter

Physical

Storage

/dev/rdsk/c6t2d1 /dev/rdsk/c11t2d1

Also, the same storage resource, virtual or attached, cannot be simultaneously shared between

virtual machines, unless otherwise specifically exempted. Figure 7-5 shows a Virtual LvDisk

being shared across virtual machines, which is not supported.

7.2 Configuring Integrity VM Storage 89