Server and workstation models

The BMC_ComputerSystem class is the core of the server model and is connected through relationships to configuration items (CIs) that represent other aspects of the server. The server and workstation model takes into account the Name, CTIs, Capabilities, and other attributes. Each class instance in a server model has all the attributes, such as Name, ShortDescription, and Category that is inherited from the BMC_BaseElement class. However, each attribute populated in a particular class is unique. For example, both the BMC_OperatingSystem and BMC_Processor classes inherit the Description attribute. However, the data added for this attribute in BMC_OperatingSystem class is different from the data added in the BMC_Processor class.

Simple server model

The following diagram shows a simple server modeled in the Common Data Model (CDM):

Simple server model

In this diagram, the BMC_HostedSystemComponents relationship class with different values of Name is used to denote two different relationships. 

• Relationship to the operating system has Name = SYSTEMOS
• Relationship to the CPU has Name = SYSTEMHARDWARE

These relationships have directionality. Both relationships have the BMC_ComputerSystem class as their source and the other class as their destination.

Name attribute

The Name attribute is the fully qualified domain name (FQDN). 

• If the FQDN is not available, the CI is populated with the hostname.
• If neither the FQDN nor the hostname is available, the CI is populated with the IP address used to connect with the computer system.

The  Name  attribute for  BMC_ComputerSystem  is set to the FQDN of the computer system. However, the Name attribute for the BMC_Processor class is set to the logical name of the processor. Thus, if a computer system has two processors, then the names are CPU0 and CPU1.

CTI attributes

All CIs have Category, Type, Item (CTI) values. CTIs form a classification hierarchy that enables CIs to be filtered for searching and reporting. Considering the hierarchy, Category is at the top level, followed by Type at the middle level, and Item at the bottom level. For example, Category defines if the CI is a hardware or a software. If it is a hardware, then Type further specifies the characteristic of that hardware. Item information defines the exact CI.

All BMC_ComputerSystem CIs that represent a server or a workstation have the following CTI values:

• Category denotes the Hardware
• Type denotes the Processing Unit
• Item denotes the Server

CTI values are often described as Hardware/Processing Unit/Server when modeling servers and workstations. But when defining other models, for example, when defining a switch, CTI values for the BMC_ComputerSystem class are Network/Switch/Data Switch.

Considering the example of a simple server model, the CTIs for the respective CIs are given in the following table:

CapabilityList and PrimaryCapability attributes

CapabilityList and PrimaryCapability are the two important attributes of the BMC_ComputerSystem class.

The CapabilityList attribute contains a list of capabilities, such as server or storage that a server has. Often, this list contains just a single item. However, sometimes it is necessary to include more than one item. For example, if a computer acts as both a server and a firewall, then the CapabilityList attribute has both of these values. The values in the list are ordered by the relative importance of each capability, with the primary capability of the computer system listed first. The capability list is a string and uses textual representations of the capabilities, rather than the numeric IDs. Semi-colons are used to separate the values in the list.

PrimaryCapability is the primary capability of the computer system. It always corresponds to the first item in the CapabilityList because the CapabilityList is ordered by importance. PrimaryCapability is an enumerated type, which means that it takes a fixed set of predefined values, each of which is assigned a number (the numeric ID). It is this number that is stored and not the textual representation of the value.

If there are two computer systems in a model, in which one computer system acts as a server, and the second computer system acts as a server and a firewall but its primary capability is that of a firewall, then the following is applicable:

For the first computer system:

• PrimaryCapability is set to 14 (ID for Server)
• CapabilityList is set to Server

For the second computer system:

• PrimaryCapability is 10 (the ID for Firewall)
• CapabilityList is set to Firewall;Server

Virtualization, software, and networking

Servers and workstations may be physical or virtual systems. The CDM treats servers and workstations in either environment in the same way because the same set of classes are used.

The two main differences between modeling physical and virtual systems are:

• Additional classes are used to model aspects of the virtualized environment
• CPUs are modeled differently