HP-UX vPars and Integrity VM V6.1.5 Administrator Guide (5900-2295, April 2013)

Figure 8 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 9 shows a Virtual LvDisk being
shared across virtual machines, which is not supported.
Figure 9 Bad Virtual Device Allocation
Guest A Guest B
Virtual
LvDisk
As these examples illustrate, it is important to know where storage is allocated from to avoid data
corruption with vPars/VMs or even the VSP. Management utilities such as the HP System
Management Homepage (HP SMH) utility allow you to track disk devices, volume groups, logical
volumes, and file systems. You can use these utilities to annotate devices so that VSP administrators
can see exactly which virtual machines are using each VSP storage device.
To show each disk only once, management utilities consolidate multipath devices into one disk.
When you are dividing up the disk, you should use all the parts of a single disk on a single virtual
machine. Allocating different parts of the same disk to different virtual machines makes it difficult
to manage and to isolate problems.
When an LVM volume group is deactivated, the storage (physical volumes) used by that storage
is designated as unused by HP-UX system administration tools such as System Management
Homepage (SMH). This is also true for Integrity VM storage management. As a result, these physical
volumes are not automatically protected from use by virtual machines as virtual disks.
You can resolve this problem in one of two ways:
• If the volume group is to remain deactivated, the VSP administrator can manually add the
physical volume as a restricted device with the hpvmdevmgmt command.
• Or, after activating the volume group, execute the hpvmhostrdev command, so that the VSP
storage management database is updated accordingly.
An HP-UX system administrator can deactivate a volume group using the vgchange command. It
can also be deactivated, if it is a shared LVM (SLVM) volume group, whenever the associated
Serviceguard cluster is reconfigured, or the VSP system is rebooted. Take care to check that all
SLVM volume groups are activated after a VSP reboot or Serviceguard cluster reconfiguration.
122 Creating virtual storage devices