Virtual systems design model

areIn the Common Data Model, two design patterns are used to represent virtualization techniques:

• A design pattern that considers the host to be running inside a virtual machine. This design pattern denotes software based machine emulation for a virtual machine.
• A design pattern that considers the host to be running on a fractional allocation of the underlying physical hardware. This design pattern denotes fixed partitioning of a larger hardware resource.

The BMC_VirtualSystemSettingData class (derived from BMC_Settings) is an important class in virtualization as it contains vital information related to virtualization. This class provides additional granularity about a virtual system’s settings through a set of virtualization-specific properties.

Virtual machine design pattern

This design pattern is appropriate where the supporting system is one of the following:

• A conventional operating system running a third party or internal virtual machine by using virtualization technology
• A kernel micro-partitioning scheme such as Solaris Containers or IBM POWER Systems Workload Partitions (WPARs)
• Bare metal virtual-machine-based hypervisors, such as VMware ESX and Microsoft Hyper-V

The virtual machine model design pattern is not appropriate for Chassis Blade type systems and Hardware partitioning based hypervisors, such as Solaris LDOM or IBM POWER Systems Dynamic Logical Partitions (DLPAR).

By design, a system running on a virtual machine must be indistinguishable from the one running on a physical machine. Because of these conceptual and practical reasons, the BMC_ComputerSystem class and attributes are used for both systems.

To distinguish the two types of machine, the BMC_ComputerSystem.isVirtual attribute flag is set. The isVirtual attribute values include:

• 1(Yes) if the system is known to be running on a virtual machine
• 0(No) if the system is known to be running on a physical machine
• NULL if neither state is known with sufficient confidence
  
  

Virtual systems design pattern

While the design pattern accounts for systems to be explicitly marked as physical, most data sources do not set BMC_ComputerSystem.isVirtual to 0 (No). If you wish to set the isVirtual attribute strictly correct, data from different sources often does not reconcile. In these circumstances, leave the value as NULL.

In the following virtual systems model design pattern:

• A shows a virtual system, thus denoted as BMC_ComputerSystem.isVirtual is set to 1 (Yes).
• B shows system which could either be physical or virtual. In such case, the BMC_ComputerSystem.isVirtual and BMC_ComputerSystem.ManufacturerName attributes are set to NULL.
• C shows a physical system denoted as BMC_ComputerSystem.isVirtual is set to NULL.

Virtual systems design model

To show the technology aspects of the virtualization, an instance of BMC_VirtualSystemEnabler is used. This is a single instance per supporting system. It is related to the supporting system by BMC_HostedSystemComponents with Name=HOSTEDSYSTEMCOMPONENTS) where the supporting system is the source and the virtualization technology is the destination. It is related to the virtual systems by BMC_Dependency with Name=VIRTUALSYSTEMOS where the virtualization technology is the source and the virtual systems is the destination.

The following diagram shows a physical virtual machine system supporting two virtual systems. To show the dependency of the virtual systems on the supporting system, the BMC_ComputerSystem virtual system instances are related to the supporting BMC_ComputerSystem instance by using BMC_Dependency relationship with Name=HOSTEDVIRTUALSYSTEM.  

• A shows the technology details such as version, type, and so on.
• B and C show two virtual machines, with the BMC_ComputerSystem.isVirtual attribute set to 1 (Yes).
• D shows the physical server which retains the BMC_ComputerSystem.isVirtual value as NULL to ease reconciliation.

Partitioned host design model

Partitioned host design pattern is based on the division of a single server into several completely independent logical partitions, where each partition is an independent virtual server. This design pattern is appropriate for hardware partitioning-based hypervisors such as an Oracle Solaris LDOM or IBM POWER Systems Dynamic Logical Partitions (DLPAR). 

An instance of BMC_VirtualSystemEnabler is used to represent the virtualization technology software that enables virtualization. This is a single instance per supporting system. It is related to each of the partitioned systems by BMC_HostedSystemComponents with Name=HOSTEDSYSTEMCOMPONENTS, where the partitioned system is the source and the virtualized technology (BMC_VirtualSystemEnabler) is the destination. It is related to the virtual systems by BMC_Dependency with Name=VIRTUALSYSTEMOS, where the virtualization technology (BMC_VirtualSystemEnabler) is the source and the virtual systems are the destination.