Top Ten Tips for Using Integrity Virtual Machines

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#6 – Do Not Exceed the Maximum Supported Number of
Virtual Storage Devices
Symptoms: Functionality
Virtual storage devices (disk or DVD) do not respond to I/O transactions or are otherwise inoperable.
Prevention and Treatment
Version 2.0 of Integrity VM supports up to 30 virtual storage devices per virtual machine. In the event
that your virtual machine needs capacity provided by more than 30 LUNs, then you may have to
consider combining some of LUNs into logical volumes on the VM Host and then using these logical
volumes to define your virtual disks.
In previous versions, the limit is 15 virtual storage devices per virtual machine. Note that in these
releases the limit was not enforced, resulting in inadvertently creating configurations which exceeded
the limit. Version 2.0 enforces this limit.
#7 – Do Not Share Disks Between Guests and the VM Host
Symptoms: Functionality, Reliability
Both the VM Host and its guests may experience widespread data corruption and severe system
reliability problems.
Prevention and Treatment
Take care in what storage is used to define virtual machine devices. Integrity VM will, by default,
prevent sharing amongst virtual machines, but cannot protect the VM Host’s storage from being
shared with guests. Use the hpvmdevmgmt CLI to designate storage used by the VM Host as
restricted devices. This should include all disks and logical volumes used by the VM Host (e.g., its file
systems and root volumes).
#8 – Do Not Use Hardware Monitoring Tools in a VM
Symptoms: Functionality
Hardware monitoring applications running in the guest will provide information about virtual devices
– at best. Such tools may not be used to measure physical hardware utilization due to the
virtualization of hardware by Integrity VM.
Prevention and Treatment
Monitor actual hardware on the VM Host. Tools such as top, glance and others will report actual
hardware information when executed on the VM Host. For examples of how to monitor the utilization
of hardware by individual virtual machines, see the white paper “Best Practices for Using Integrity
Virtual Machines.”
Hardware utilization tools such as top and glance may be useful to run in a virtual machine to monitor
virtual CPU utilization. Keep in mind that the utilization of virtual hardware – i.e., the virtual
machine’s share of the physical resource – will be reported by such tools. The virtual machine’s share
of a given hardware resource may change rapidly, especially in the case of virtual CPUs. Use
hardware monitoring tools – including those provided with Integrity VM – on the VM Host system to
measure a virtual machine’s share of a given hardware resource.