Host node

A Host node represents a general purpose computer on the network; any physical or virtual computer system in your organization. A host is of a specific type, such as a server or a desktop which BMC Discovery gains high quality interactive access to. A host is not an IP-connected device, such as a switch or a router.

The attributes of a Host node contain stable information about the host, such as processor and memory details, its primary host name, OS information, whether it is virtual, and so forth. Hosts are considered inferred information because rules inside the reasoning engine are used to determine which hosts exist based on the DiscoveryAccess results obtained. Hosts will only be created for discovery targets that should be considered hosts, as opposed to switches, printers or other infrastructure.

Host node lifecycle

The following section describes the scenarios in which a Host node is created, updated or destroyed automatically.

Creation/update

In order to maintain the model of hosts in the environment, BMC Discovery identifies hosts using an internal weighting algorithm, see Uniquely Identifying a Host for more information. Hosts are identified by a number of criteria using this algorithm. The creation, update and removal of a Host node are based on these identities.

A Host node is created in the datastore when a new host is inferred from a successful discovery. A Host is only created when good quality access to the target computer has been established. Good quality access is necessary for the BMC Discovery internal system to establish that there is sufficient stable information available to identify a Host. Stable information is considered to be data such as hardware details, how many active interfaces there are, bios serial numbers and so forth.

A Host node is not created unless information is available from the getDeviceInfo, getHostInfo. The getMACAddresses method must also be successful except in the case where vCenter is scanned using vSphere.

For as long as BMC Discovery's host identification algorithm can determine that a particular discovery target corresponds to a particular Host node, the Host node is updated every time the target is scanned on any of its IP addresses. Once a Host node is created, BMC Discovery will update its attributes as the host changes over time, while still retaining the original Host node and key.

When a Host node is first created, BMC Discovery constructs a key attribute that uniquely identifies the host. The key is based on a combination of attribute values from the Host, but those attributes can change over time. As the host is rescanned, the Host node attributes that contributed to the key can all change, but the key itself will not be changed. If a Host node is destroyed and then the corresponding host is rescanned, a new Host node will be created. If the attribute values that were originally used to construct the key have not changed, the new Host node will be given the same key as the original one, but if any of the attributes have changed, the new Host node will have a different key to the old one.

Removal

Host node can be destroyed either manually or automatically.

To remove a host node manually, find the host, select it in the list and pick Destroy from the Actions list.

By default, a Host node will be automatically destroyed, if BOTH of the following circumstances are fulfilled:

No update has been made in ten days from any of the IP addresses known for this host.
No update has been made in the last seven scans on the IP address currently being scanned.

Thus, if a host is not successfully scanned, by default, the Host node representing it will remain in the model for at least 10 days. In this context, "seen" means anything other than no update. The table below shows the default removal criteria for the Host node.

These are the default settings for the number of days and number of scans. You can change these settings on the Model Maintenance page. See Configuring-model-maintenance-settings for more information.

When a Host node is destroyed, its related nodes are destroyed too. That is, if a Host node is destroyed, all of its software instances, network interfaces, files, and HBAs are also destroyed.

When a node with attachments is destroyed, the attachments are not destroyed, and remain attached to the destroyed node. See Attachments for an introduction to attachments.
If a host node is destroyed from the datastore, all of its relationships are destroyed as well. For example, a host might have a relationship to a location. If the host is destroyed, the relationship to that location will also be destroyed. See How-nodes-are-removed.

Uniquely Identifying a Host

There is no single identifying attribute that can be used reliably to identify hosts. BMC Discovery determines host identities using an internal host identification algorithm to select which existing Host node should be connected, if any, with the Directly Discovered Data from the current scan.

A Host node is only created or updated when BMC Discovery has enough information to determine that a suitable Host node does not already exist or that an existing Host node is the one to use. A host will not be created or updated unless BMC Discovery has working credentials to extract enough information from the host.

Once BMC Discovery has sufficient information on the scanned endpoint it searches in the datastore for candidate Host nodes to be updated. This is carried out using a series of search queries, for example:

Host previously updated via a scan from this endpoint.
Host with one of its IP addresses being the endpoint scanned.
Host with the same bios serial number as the scanned endpoint.

The Host nodes returned by these, and other searches, are candidates for being linked with the scanned Discovery Access node.

All the candidates are then ranked using the BMC Discovery algorithm based on the data on the candidate and the data currently retrieved from the endpoint. Each attribute on the host could be one of the following:

Confirmed - same attribute key, same value.
Changed - the value on the host for that attribute key is different from the value scanned.
Absent - the value is set on the candidate, but is no longer available in the scanned data.

For each attribute a score is set for confirmed, changed or absent values. These scores are then added together to build the ranking. The score for all the attributes are then added together.

Once all the candidates have been evaluated, Host nodes with a negative ranking are ignored, and the highest positive-ranked Host node will be chosen. If no Host nodes have a positive score, or if no candidates have been found, a new Host node is created. In all cases, the Host node is then updated with the new data.

Endpoint identity

BMC Discovery scans IP addresses, or endpoints. It is the job of the Host identification algorithm to match endpoints to Host nodes. When an endpoint is scanned, the host identification algorithm sometimes decides that the endpoint now corresponds to a different Host node to the previous scan of that endpoint. This can happen for three main reasons:

IP addresses have been reassigned so the endpoint really does correspond to a different host.
The endpoint still corresponds to the same host, but the host has changed so much since the previous scan that BMC Discovery cannot tell that it is the same one.
The endpoint still corresponds to the same host, but BMC Discovery's access credentials have changed substantially, meaning the data appears very different. This can happen when switching between SNMP and login access, for example.

All three situations look the same from BMC Discovery's point of view — the discovered data is significantly different from the data previously retrieved from the endpoint. To facilitate understanding of these scenarios, BMC Discovery creates an EndpointIdentity relationship between the Host nodes. The Host view displays the relationship and allows comparison of the new and old Host nodes.

In all situations, BMC Discovery will ultimately resolve the condition. If the change is due to an IP address reassignment, the original Host can be found by scanning a different endpoint. If that happens, the Host is connected to the new endpoint and the EndpointIdentity relationship is removed. In other situations, the original Host node will age out according to the normal ageing rules.

Virtualization and Consolidation

BMC Discovery performs consolidation of virtual and partitioned hosts. When it does this, the model it constructs is as follows:

Virtual Hosts - see Virtual Hosts.
Contained Hosts - see Contained Hosts.
Clustered Hosts - see Clustered Hosts.

Virtual Hosts

Virtual Hosts are modeled so that the virtual host is related through the virtual machine to the physical host. For example:

VMware Virtual Machines
Solaris Containers

Contained Hosts

Where a number of IP devices are discovered that are logical devices on hosts, they are modeled as shown in the diagram below. See Host node lifecycle.
For example, the following types of servers are treated in this manner:

Sun Enterprise 10000 - E10K
Sun Fire 12000 - F12K
Sun Fire 15000 - F15K
Sun Fire 20000 - F20K
Sun Fire 25000 - F25K

Clustered Hosts

Where a number of collaborative hosts are discovered (they are seen as individual IP devices and there is no parent), they are consolidated into clusters which are modeled as Cluster nodes, see Cluster node lifecycle. For example, the following types of cluster are treated in this manner:

Microsoft Clusters
Veritas Cluster Servers

Host node attributes

The attributes and relationships of a Host node are described in the tables below. Where hidden attributes are included, they are described in the most relevant section. Not all attributes are discovered for every platform, see the Discovered attributes by platform page for information on this.

Fields that are displayed in the user interface but have no related attribute on a Host node, that is, they are inherited or populated by relationships, are also shown.

Name name : string	Primary name.
Short Name short_name : string	Short name.
Description description : string	Description of the element.
URL url : string	URL for information about the element.
Business Continuity Critical business_continuity_critical : boolean	If true, element is critical to operation of the business.
Supported by 3rd Party third_party_support : boolean	True if the element is supported by a third party.
Synonyms synonyms : list:string	Other names for the element.

UI Name Attribute Name and Type	Description
General Details
Hostname hostname : string	Hostname.
Key key : string	Globally unique key.
Name name : string	Primary name.
Short Name short_name : string	Short name.
Description description : string	Description of the element.
URL url : string	URL for information about the element.
Business Continuity Critical business_continuity_critical : boolean	If true, element is critical to operation of the business.
Supported by 3rd Party third_party_support : boolean	True if the element is supported by a third party.
Synonyms synonyms : list:string	Other names for the element.
Not displayed in UI host_type : string	Type classification of the Host such as 'UNIX Server', 'Windows Desktop', and so on (DEPRECATED - use attribute type).
Type type : string	Type classification of the Host such as 'UNIX Server', 'Windows Desktop', and so on.
OS os : string	Operating system.
OS Type os_type : string	Operating system type.
OS Class os_class : string	Operating system class.
OS Version os_version : string	Operating system version.
OS Edition os_edition : string	Operating system edition.
OS Update Level os_level : string	Operating system update level.
OS Architecture os_arch : string	Operating system architecture.
OS Vendor os_vendor : string	Operating system vendor.
OS Release Name os_release_name : string	Operating release name.
OS Build os_build : string	Operating system build information.
Service Pack service_pack : int	Service pack.
Kernel kernel : string	Kernel version.
Unique Host Id hostid : string	Unique Host identification string.
Number of Processors num_processors : int	The number of physical processors.
Processor Type processor_type : string	The type of each processor.
Processor Speed processor_speed : int	The speed of each processor in MHz.
Number of Logical Processors num_logical_processors : int	The number of logical processors available to the OS.
Cores per Processor cores_per_processor : int	The number of cores per processor.
Threads per Processor Core threads_per_core : int	The number of threads per core in multi/hyper threaded processors.
CPU Threading Enabled cpu_threading_enabled : boolean	Whether CPU hardware threading is enabled.
Number of Processor Types num_processor_types : int	The number of physical processor types.
All Processor Types _all_processor_types : list:string	List of all processor types.
All Processor Speeds _all_processor_speeds : list:int	List of all processor speeds.
Logical Processor Counts _all_processor_logical_counts : list:int	List of logical processor counts.
Physical Processor Counts _all_processor_physical_counts : list:int	List of physical processor counts.
Not displayed in UI _all_threads_per_core : list:int	List of threads per core counts.
Not displayed in UI _all_cores_per_processor : list:int	List of cores per processor counts.
Physical RAM ram : int	The amount of RAM (in MB) installed on the host, as reported by the OS.
Logical RAM logical_ram : int	The amount of RAM (in MB) available on the host, as reported by the OS.
Virtual virtual : boolean	Flag if the Host is virtual.
Cloud Hosted cloud : boolean	When set, this flag indicates that the Host runs directly on a cloud service.
Partition partition : boolean	Flag if the Host is a partition.
Virtualization Class vm_class : string	Class of virtual machine.
E10K SSP Hostname ssphostname : string	E10K SSP Hostname.
SunFire Domain sunfire_domain : string	F15K SunFire domain.
Zonename zonename : string	Solaris Zonename.
Zone UUID zone_uuid : string	Solaris Zone UUID.
LDOM Name ldom_name : string	Solaris LDOM name.
LDOM Role ldom_role : string	Solaris LDOM role.
Power LPAR Node Name lpar_node_name : string	IBM Power LPAR node name.
Power LPAR Name lpar_name : string	IBM Power LPAR partition name.
Power LPAR Number lpar_partition_number : int	IBM Power LPAR partition number.
Power LPAR Group lpar_partition_group_id : int	IBM Power LPAR partition group id.
IP Address of Manager management_ip_addr : string	IP address of management system.
Identity
Local FQDN local_fqdn : string	Fully qualified domain name reported by the Host.
DNS Domain dns_domain : string	DNS domain the Host belongs to.
NIS/Windows Domain domain : string	Windows or NIS domain the Host belongs to.
Windows Workgroup workgroup : string	Windows workgroup the Host belongs to.
Operating System
Hardware Vendor vendor : string	Hardware vendor.
Model model : string	Hardware model.
Product Model product_model : string	Hardware model publicised by the vendor.
Serial Number serial : string	Serial number.
UUID uuid : string	UUID.
Power Supply Status psu_status : list:string	Power Supply Unit status.
Patches and Packages
Package Count package_count : int	Number of packages.
Patch Count patch_count : int	Number of patches.
Attributes used internally to short circuit some processing
Not displayed in UI age_count : int	The number of consecutive successful (positive) or failed (negative) accesses, from any endpoint.
Not displayed in UI last_update_success : date	The time at which a scan was last successfully associated with this host. The "last_update_success" for Hosts is formatted in this way: Last Update Success 2016-09-17 14:17:40.624471+00:00
Not displayed in UI last_update_failure : date	The time at which a scan associated with this Host failed.
Not displayed in UI last_access_response : string	Response from last attempt to access Host.
Not displayed in UI no_response_count : int	Number of no responses since last success.
Not displayed in UI access_failure_count : int	Number of access failures since last success.
Not displayed in UI new_endpoint_identity_count : int	Number of access where endpoint reports different device.
Not displayed in UI __patch_checksum : string	Checksum for Patch information to determine if new information differs.
Not displayed in UI __package_checksum : string	Checksum for Package information to determine if new information differs.
Not displayed in UI __all_ip_addrs : list:string	Internal attribute to aid searching Hosts by IP address, these may include IPs from network interfaces and scanned IPs and no specific behaviour of this field should be relied upon.
Not displayed in UI __all_dns_names : list:string	Internal attribute to aid searching Hosts by name.
Not displayed in UI _excluded_from_grouping : boolean	Internal attribute to record that a node has been marked as excluded from automatic grouping.
Attributes used for CMDB Sync
CDM Virtual System Type cdm_virtual_system_type : int	Attribute for populating the CDM BMC_ComputerSystem.VirtualSystemType attribute.
Last successful CMDB sync last_cmdb_sync_success : date	The time at which this Host was last successfully synchronized into the CMDB.
Last failed CMDB sync last_cmdb_sync_failure : date	The time at which an attempt to synchronize this Host into the CMDB failed.
CMDB sync duration last_cmdb_sync_duration : float	The time in seconds spent performing the last CMDB synchronization of this Host.
CMDB CI count last_cmdb_sync_ci_count : int	The number of CIs corresponding to this Host at the last CMDB synchronization.
CMDB Relationship count last_cmdb_sync_rel_count : int	The number of relationships between CIs corresponding to this Host at the last CMDB synchronization.
Other
Scope scope : string	Distinguish overlapping address spaces.
AWS EC2 Instance ID aws_instance_id : string	AWS EC2 instance identifier.
Azure VM ID azure_vm_id : string	Azure VM identifier.
GCE Instance ID gce_instance_id : string	GCE instance identifier.
OpenStack Nova Instance ID openstack_instance_id : string	OpenStack Nova instance identifier.

Host node relationships

The relationships on a Host node are as described in the following table:

UI name	Relationship	Description
Containing AutomaticGroup	Host: ContainedItem: Containment: Container: AutomaticGroup	Owning AutomaticGroup.
Containing Group	Host: ContainedItem: Containment: Container: Group	Owning Group.
Hosted Applications	Host: Host: HostedSoftware: AggregateSoftware: BusinessApplicationInstance	Business Application Instances running on this Host.
Software Clusters	Host: Host: HostedSoftware: AggregateSoftware: SoftwareCluster	Software Clusters running on this Host.
Software Instances	Host: Host: HostedSoftware: RunningSoftware: SoftwareInstance	Software Instances running on this Host.
Software Containers	Host: Host: HostedSoftware: RunningSoftware: SoftwareContainer	Software Containers running on this Host.
Virtual Machines	Host: Host: HostedSoftware: RunningSoftware: VirtualMachine	Virtual Machines running on this Host.
Clustered Software Instances	Host: Host: HostedSoftware: ClusteredSoftware: SoftwareInstance	Clustered Software Instances running on this Host.
Aggregate Software Instances	Host: Host: HostedSoftware: AggregateSoftware: SoftwareInstance	Aggregate Software Instances running on this Host.
Candidate Software Instances	Host: Host: HostedSoftware: RunningSoftware: CandidateSoftwareInstance	Candidate Software Instances running on this Host.
Unassigned Connections	Host: Host: HostedSoftware: RunningSoftware: UnassignedConnections	Unassigned Connections observed on this Host.
Runtime Environments	Host: Host: HostedSoftware: RunningSoftware: RuntimeEnvironment	Runtime Environments on this Host.
Hardware Container	Host: ContainedHost: HostContainment: HostContainer: HardwareContainer	Hardware container of which this is a member.
Host Container	Host: ContainedHost: HostContainment: HostContainer: HostContainer	Host container of which this is a member.
Cluster	Host: ContainedHost: HostContainment: HostContainer: Cluster	Cluster of which this is a member.
Cluster Member	Host: ServiceHost: SoftwareService: Service: ClusterMember	Cluster member that this host represents.
Containing VM	Host: ContainedHost: HostContainment: HostContainer: VirtualMachine	Software container for this virtual Host.
Network Interfaces	Host: DeviceWithInterface: DeviceInterface: InterfaceOfDevice: NetworkInterface	Network interfaces of this Host.
IPv4 Addresses	Host: DeviceWithAddress: DeviceAddress: IPv4Address: IPAddress	IPv4 addresses of this Host.
IPv6 Addresses	Host: DeviceWithAddress: DeviceAddress: IPv6Address: IPAddress	IPv6 addresses of this Host.
Fibre Channel HBAs	Host: DeviceWithInterface: DeviceInterface: InterfaceOfDevice: FibreChannelHBA	Fibre Channel HBAs of this Host.
Files	Host: Host: HostedFile: HostedFile: File	Files on this Host.
Device Info	Host: InferredElement: Inference: Primary: DeviceInfo	DeviceInfo of this Host.
Host Info	Host: InferredElement: Inference: Primary: HostInfo	HostInfo of this Host.
Discovery Access	Host: InferredElement: Inference: Associate: DiscoveryAccess	DiscoveryAccess for this Host.
Patches	Host: Host: HostedSoftware: InstalledSoftware: Patch	Patches on this Host.
	Host: InferredElement: Inference: Contributor: DiscoveredPatches	Patches contributing to this Host's attribute.
Packages	Host: Host: HostedSoftware: InstalledSoftware: Package	Packages on this Host.
	Host: InferredElement: Inference: Contributor: DiscoveredPackages	Packages contributing to this Host's attribute.
File Systems	Host: Mounter: FileSystemMount: MountedFileSystem: FileSystem	FileSystems of this Host.
Disk Drives	Host: Container: Containment: ContainedDrive: DiskDrive	DiskDrives contained in this Host.
Disk Drives Used	Host: Consumer: StorageUse: Provider: DiskDrive	DiskDrives used by this Host.
Storage Volumes	Host: Consumer: StorageUse: Provider: StorageVolume	Storage Volumes used by this Host.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: Host	Previous Host Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: Host	Next Host Identity.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: NetworkDevice	Previous Network Device Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: NetworkDevice	Next Network Device Identity.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: Mainframe	Previous Mainframe Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: Mainframe	Next Mainframe Identity.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: Printer	Previous Printer Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: Printer	Next Printer Identity.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: SNMPManagedDevice	Previous SNMP Managed Device Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: SNMPManagedDevice	Next SNMP Managed Device Identity.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: ManagementController	Previous Management Controller Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: ManagementController	Next Management Controller Identity.
Endpoint Used To Be Identified As	Host: Next: EndpointIdentity: Previous: StorageDevice	Previous Storage Device Identity.
Endpoint Now Identified As	Host: Previous: EndpointIdentity: Next: StorageDevice	Next Storage Device Identity.
Chosen Endpoint	Host: Device: ChosenEndpoint: Endpoint: Endpoint	Endpoint used to discover this Host.
Hardware Reference Data	Host: Hardware: ReferenceData: ReferenceData: HardwareReferenceData	Hardware Reference data corresponding to this Host.
Hardware Support Details	Host: ElementWithDetail: SupportDetail: HardwareDetail: SupportDetail	Hardware Support Detail related to this Host.
OS Support Details	Host: ElementWithDetail: SupportDetail: OSDetail: SupportDetail	OS Support Detail related to this Host.
Details	Host: ElementWithDetail: Detail: Detail: Detail	Details of this Host.
Collections	Host: Member: Collection: Collection: Collection	A collection which this Host is a member of.
Administrative Collections	Host: Member: Collection: Collection: AdminCollection	An administrative collection which this Host is a member of.
Communicating With	Host: Host: ObservedCommunication: Host: Host	Other Hosts that this Host is communicating with.
Managed by Software Instance	Host: ManagedElement: Management: Manager: SoftwareInstance	Software Instances that manage this Host.
Managed by SNMP Managed Device	Host: ManagedElement: Management: Manager: SNMPManagedDevice	SNMP Managed Device that manages this Host.
Managed by Management Controller	Host: ManagedElement: Management: Manager: ManagementController	Management Controller that manages this Host.
Manages Storage Systems	Host: Manager: Management: ManagedElement: StorageSystem	Storage systems on this device.
Managed By Network Devices	Host: ManagedElement: Management: Manager: NetworkDevice	NetworkDevices that manage this Host.
Discovery Conditions	Host: ElementWithCondition: DiscoveryCondition: DiscoveryCondition: DiscoveryCondition	Discovery conditions to which this element pertains.
Discovery Access Failure	Host: InferredElement: AccessFailure: DiscoveryAccess: DiscoveryAccess	The failed access for an endpoint.
Discovery Access Optimization	Host: InferredElement: AccessOptimization: DiscoveryAccess: DiscoveryAccess	The optimized access for an endpoint.
Load Balancer	Host: ServiceHost: SoftwareService: Service: LoadBalancerMember	Load balancer member.
Processor Information	Host: Host: Detail: Hardware: ProcessorInfo	Processor information.
	Host: AttachmentContainer: Attachment: Attachment: Attachment	A file attached to this element.
Status	Host: ElementInCategory: ElementCategory: Category: LifecycleStatus	The lifecycle status of this element.
Recovery Time	Host: ElementInCategory: ElementCategory: Category: RecoveryTime	The recovery time specified for this element.
Family	Host: ElementInCategory: ElementCategory: Category: Family	Family of this element.
Organizational Unit	Host: OwnedItem: Ownership: Owner: OrganisationalUnit	The Organizational Unit that this element belongs to.
Location	Host: ElementInLocation: Location: Location: Location	Location of this element.
Support Manager	Host: OwnedItem: Ownership: SupportOwner: Person	The person or owner responsible for the support of this element.
Business Owner	Host: OwnedItem: Ownership: BusinessOwner: Person	The person or owner responsible for this element from a business perspective.
IT Owner	Host: OwnedItem: Ownership: ITOwner: Person	The person or owner responsible for this element from an IT perspective.