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 be successful too excepted in the case of vCenters scanned with 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

A 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.

Node Kind	Days	Scans
Host	10	7

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.

UI Name `Attribute Name` and `Type`	Description
General Details
`name string`	The name that the host is known by, typically the same as hostname.
Not displayed in UI `hostname string`	The name that the host is known by systems external to this host.
Not displayed in UI `key string`	Globally unique key.
Short Name short_name string	Short name.
Not displayed in UI `description string`	Description of the host. Legacy attribute not currently used. Can be used by patterns if desired.
Not displayed in UI `url string`	URL for information about the host. Legacy attribute not currently used. Can be used by patterns if desired.
Not displayed in UI `business_continuity_critical boolean`	If true, the host is critical to operation of the business. Legacy attribute not currently used. Can be used by patterns if desired
Not displayed in UI `third_party_support boolean`	If true, the host is supported by a third party. Legacy attribute not currently used. Can be used by patterns if desired
Not displayed in UI `synonyms list:string`	Other names by which this host is known. Legacy attribute not currently used. Can be used by patterns if desired
Not displayed in UI `host_type string`	Type such as 'UNIX Server', 'Windows Desktop', and so on. This attribute is deprecated, use `type` instead.
Type `type string`	Type such as 'UNIX Server', 'Windows Desktop', and so on.
Hardware Vendor `vendor string`	The hardware vendor, for example, Dell Computer Corporation.
Virtual `virtual boolean`	Flag if the host is virtual.
Partition `partition boolean`	Flag if the host is a partition.
Virtualization Class `vm_class_string_`	Class of virtual machine.
E10K SSP Hostname `ssphostname string`	The E10K SSP Hostname, the physical host for a Sun Microsystems "Blade" Servers. This is available on Sun Enterprise 10000 systems only.
SunFire Domain `sunfire_domain string`	F15K SunFire domain. Common to all blades in a SunFire server. The attribute is set for all Host nodes which are members of the server.
Zonename `zonename string`	The Solaris Zonename of this host and its container. Currently only Solaris 10 supports zonenames.
LDOM Name `ldom_name string`	Solaris LDOM name.
LDOM Role `ldom_role string`	Solaris LDOM role.
Power LPAR Name `lpar_name string`	IBM Power LPAR Name.
Power LPAR Number `lpar_partition_number : int`	IBM Power LPAR Number.
Product Model `product_model string`	The model name publicized by the vendor. Only set when different from Model.
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.
Identity
Local FQDN `local_fqdn string`	The fully qualified domain name of the host.
DNS Domain `dns_domain string`	The DNS domain to which the host belongs.
NIS/Windows Domain `domain string`	The NIS/Windows domain to which the host belongs.
Windows Workgroup `workgroup string`	The Windows workgroup to which this host belongs.
Operating System
OS `os string`	The name and version of the Operating system. For example, Mandrake Linux release 9.1 (Bamboo) for i586.
OS Class `os_class string`	Operating system class.
OS Type `os_type string`	Operating system type. The name part of the os attribute. For example, Mandrake Linux.
OS Version `os_version string`	Operating system version. The version part of the os attribute. For example, 9.1.
OS Edition `os_edition string`	Operating system edition.
OS Architecture `os_arch string`	Operating system architecture.
OS Update Level `os_level string`	Operating system update level.
OS Build `os_build string`	Operating system build information.
OS Vendor `os_vendor string`	Operating system vendor.
Service Pack `service_pack int`	Service Pack number. Windows only.
Kernel `kernel string`	The version of the kernel. For example, on an AIX host, 5.3.
Patches and Packages
Package Count `package_count int`	The number of packages.
Patch Count `patch_count int`	The number of patches.
Attributes used internally to short circuit some processing
Not displayed in UI `__patch_checksum string`	The patch checksum.
Not displayed in UI `__package_checksum string`	The package checksum.
Host aging attributes
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 changed in BMC Discovery 11.0. In earlier versions it was formatted in this way: Last Update Success 2016-09-17 14:17:40.62 In BMC Discovery 11.0 and later versions it 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.
Hardware and Network
Model `model string`	The model name of the hardware.
Serial Number `serial string`	The serial number of the hardware.
UUID `uuid string`	The universally unique identifier (UUID) of the host.
Unique Host Id `hostid string`	Unique Host identification string. When HP-UX partitions are scanned, the partition ID is determined and appended to the original hostid. This differentiates individual hosts in an HP-UX domain.
Logical RAM `logical_ram int`	The amount of RAM (in MB) available on the host, as reported by the OS. In some cases this might not be useful. For example, some OSs can reserve RAM for particular purposes.
Physical RAM `ram int`	The amount of RAM (in MB) installed on the host, as reported by the OS. In some cases this might not be useful. For example, physical RAM makes little sense for a host in a cloud.
Number of Processors `num_processors int`	The number of physical processors on the host.
Processor Type `processor_type string`	The type of processor used in the host. For example, Intel(R) Pentium(R) 4 CPU.
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 physical processor available to the OS.
Threads per Processor Core `threads_per_core int`	The number of threads per core in multi/hyper threaded processors available to the OS.
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.
Power Supply Status `psu_status list:string`	Displays the status for each power supply. This can be either OK or Fail.
Attributes used only to facilitate search queries
Not displayed in UI `__all_ip_addrs list:string`	BMC Discovery internal use only. Do not use. Internal attribute to aid searching Hosts by IP address.
Not displayed in UI `__all_dns_names list:string`	BMC Discovery internal use only. Do not use. Internal attribute to aid searching Hosts by name.
Attributes used for grouping
`_excluded_from_grouping boolean`	BMC Discovery internal use only. Records that a node has been marked as excluded from automatic grouping. Do not use.
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.

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.
Location	`Host: ElementInLocation: Location: Location: Location`	Location of this Host.
Hosted Applications	`Host: Host: HostedSoftware: AggregateSoftware: BusinessApplicationInstance`	Business Application Instances running on this Host.
Software Instances	`Host: Host: HostedSoftware: RunningSoftware: SoftwareInstance`	Software Instances running on this Host.
Aggregate Software Instances	`Host: Host: HostedSoftware: AggregateSoftware: SoftwareInstance`	Aggregate Software Instances running on this Host.
Runtime Environments	`Host: Host: HostedSoftware: RunningSoftware: RuntimeEnvironment`	Runtime Environments on this Host.
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.
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.
Not displayed in UI	`Host: InferredElement: Inference: Contributor: DiscoveredPatches`	Patches contributing to this Host's attributes.
Packages	`Host: Host: HostedSoftware: InstalledSoftware: Package`	Packages on this Host.
Not displayed in UI	`Host: InferredElement: Inference: Contributor: DiscoveredPackages`	Packages contributing to this Host's attributes.
File System	`Host: Mounter: FileSystemMount: MountedFileSystem: FileSystem`	FileSystem of this Host.
Disk Drives	`Host: Container: Containment: ContainedDrive: DiskDrive`	DiskDrives contained in this Host.
Disk Drives	`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 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 Now Identified As	`Host: Previous: EndpointIdentity: Next: SNMPManagedDevice`	Next SNMP Managed Device 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.
Communicating With	`Host: Host: ObservedCommunication: Host: Host`	Other Hosts that this Host is communicating with. Only created when automatic grouping is enabled.
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.
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.
Not displayed in UI	`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 responsible for the support of this element.
Business Owner	`Host: OwnedItem: Ownership: BusinessOwner: Person`	The person responsible for this element from a business perspective.
IT Owner	`Host: OwnedItem: Ownership: ITOwner: Person`	The person responsible for this element from an IT perspective.
Clustered Software Instances	`Host: Host: HostedSoftware: ClusteredSoftware: SoftwareInstance`	Clustered 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.
Cluster Member	`Host: ServiceHost: SoftwareService: Service: ClusterMember`	Cluster member that this host represents.
Manages Storage Systems	`Host: Manager: Management: ManagedElement: StorageSystem`	Storage systems on this device.
Processor Information	`Host: Host: Detail: Hardware: ProcessorInfo`	Processor information.