CMDB Patterns for ServiceNow

The Configuration Management Database (CMDB) is the foundation of ServiceNow ITSM, tracking all Configuration Items (CIs) and their relationships.

CMDB Architecture

CI Class Hierarchy

cmdb (Base) └── cmdb_ci (Configuration Item) ├── cmdb_ci_computer │ ├── cmdb_ci_server │ │ ├── cmdb_ci_linux_server │ │ ├── cmdb_ci_win_server │ │ └── cmdb_ci_unix_server │ └── cmdb_ci_pc_hardware ├── cmdb_ci_service │ ├── cmdb_ci_service_auto │ └── cmdb_ci_service_discovered ├── cmdb_ci_appl │ ├── cmdb_ci_app_server │ └── cmdb_ci_db_instance └── cmdb_ci_network_gear ├── cmdb_ci_netgear └── cmdb_ci_lb

Key CI Tables

Table Purpose Key Fields

cmdb_ci

Base CI table name, sys_class_name, operational_status

cmdb_ci_server

Servers ip_address, os, cpu_count, ram

cmdb_ci_service

Business Services service_classification, busines_criticality

cmdb_ci_appl

Applications version, install_directory

cmdb_rel_ci

CI Relationships parent, child, type

Creating Configuration Items

Basic CI Creation (ES5)

// Create a new server CI var ci = new GlideRecord("cmdb_ci_server") ci.initialize() ci.setValue("name", "PROD-WEB-001") ci.setValue("ip_address", "10.0.1.100") ci.setValue("os", "Linux Red Hat") ci.setValue("os_version", "8.5") ci.setValue("cpu_count", 8) ci.setValue("ram", 32768) ci.setValue("operational_status", 1) // Operational ci.setValue("install_status", 1) // Installed ci.setValue("used_for", "Production") ci.setValue("owned_by", "sys_id_of_owner") ci.setValue("support_group", "sys_id_of_group") var sysId = ci.insert()

CI with Discovery Source

// CI from Discovery var ci = new GlideRecord("cmdb_ci_linux_server") ci.initialize() ci.setValue("name", "discovered-server-001") ci.setValue("discovery_source", "ServiceNow") ci.setValue("first_discovered", new GlideDateTime()) ci.setValue("last_discovered", new GlideDateTime()) ci.setValue("ip_address", "10.0.2.50")

// Set classification ci.setValue("classification", "Production") ci.setValue("environment", "Production")

ci.insert()

CI Relationships

Relationship Types

Type Parent → Child Example

Runs on::Runs

App → Server ERP runs on PROD-DB-01

Depends on::Used by

Service → App HR Service depends on SAP

Contains::Contained by

Cluster → Server Cluster contains Node1

Hosted on::Hosts

VM → Hypervisor VM01 hosted on ESX01

Members::Member of

CI → Group Server member of Pool

Creating Relationships (ES5)

// Create relationship between CIs function createCIRelationship(parentSysId, childSysId, relationType) { // Find relationship type var relType = new GlideRecord("cmdb_rel_type") relType.addQuery("name", relationType) relType.query()

if (!relType.next()) { gs.error("Relationship type not found: " + relationType) return null }

// Check if relationship already exists var existing = new GlideRecord("cmdb_rel_ci") existing.addQuery("parent", parentSysId) existing.addQuery("child", childSysId) existing.addQuery("type", relType.getUniqueValue()) existing.query()

if (existing.next()) { gs.info("Relationship already exists") return existing.getUniqueValue() }

// Create new relationship var rel = new GlideRecord("cmdb_rel_ci") rel.initialize() rel.setValue("parent", parentSysId) rel.setValue("child", childSysId) rel.setValue("type", relType.getUniqueValue()) return rel.insert() }

// Usage createCIRelationship(appSysId, serverSysId, "Runs on::Runs")

Querying Relationships

// Find all servers an application runs on function getAppServers(appSysId) { var servers = []

var rel = new GlideRecord("cmdb_rel_ci") rel.addQuery("parent", appSysId) rel.addQuery("type.name", "Runs on::Runs") rel.query()

while (rel.next()) { var server = rel.child.getRefRecord() servers.push({ sys_id: server.getUniqueValue(), name: server.getValue("name"), ip_address: server.getValue("ip_address"), }) }

return servers }

// Find all dependencies of a service function getServiceDependencies(serviceSysId) { var deps = []

var rel = new GlideRecord("cmdb_rel_ci") rel.addQuery("parent", serviceSysId) rel.addQuery("type.name", "Depends on::Used by") rel.query()

while (rel.next()) { deps.push({ sys_id: rel.child.getUniqueValue(), name: rel.child.getDisplayValue(), class: rel.child.sys_class_name.toString(), }) }

return deps }

Impact Analysis

Upstream/Downstream Analysis

// Get all CIs affected by a CI outage (downstream impact) function getDownstreamImpact(ciSysId, depth) { if (typeof depth === "undefined") depth = 3

var impacted = [] var processed = {}

function traverse(sysId, currentDepth) { if (currentDepth > depth || processed[sysId]) return processed[sysId] = true

var rel = new GlideRecord("cmdb_rel_ci")
rel.addQuery("child", sysId)
rel.query()

while (rel.next()) {
  var parentId = rel.parent.toString()
  if (!processed[parentId]) {
    impacted.push({
      sys_id: parentId,
      name: rel.parent.getDisplayValue(),
      depth: currentDepth,
    })
    traverse(parentId, currentDepth + 1)
  }
}

}

traverse(ciSysId, 1) return impacted }

// Get all CIs this CI depends on (upstream dependencies) function getUpstreamDependencies(ciSysId, depth) { if (typeof depth === "undefined") depth = 3

var dependencies = [] var processed = {}

function traverse(sysId, currentDepth) { if (currentDepth > depth || processed[sysId]) return processed[sysId] = true

var rel = new GlideRecord("cmdb_rel_ci")
rel.addQuery("parent", sysId)
rel.query()

while (rel.next()) {
  var childId = rel.child.toString()
  if (!processed[childId]) {
    dependencies.push({
      sys_id: childId,
      name: rel.child.getDisplayValue(),
      depth: currentDepth,
    })
    traverse(childId, currentDepth + 1)
  }
}

}

traverse(ciSysId, 1) return dependencies }

Business Service Impact

// Find all business services impacted by a CI function getImpactedServices(ciSysId) { var services = [] var processed = {}

function findServices(sysId) { if (processed[sysId]) return processed[sysId] = true

// Check if this CI is a service
var ci = new GlideRecord("cmdb_ci")
if (ci.get(sysId)) {
  if (ci.sys_class_name.toString().indexOf("cmdb_ci_service") === 0) {
    services.push({
      sys_id: sysId,
      name: ci.getValue("name"),
      criticality: ci.getValue("busines_criticality"),
    })
  }
}

// Traverse upstream
var rel = new GlideRecord("cmdb_rel_ci")
rel.addQuery("child", sysId)
rel.query()

while (rel.next()) {
  findServices(rel.parent.toString())
}

}

findServices(ciSysId) return services }

CMDB Health & Data Quality

Orphan CI Detection

// Find CIs without relationships function findOrphanCIs(ciClass) { var orphans = []

var ci = new GlideRecord(ciClass || "cmdb_ci") ci.addQuery("operational_status", 1) // Operational only ci.query()

while (ci.next()) { var sysId = ci.getUniqueValue()

// Check for any relationships
var rel = new GlideRecord("cmdb_rel_ci")
rel.addQuery("parent", sysId).addOrCondition("child", sysId)
rel.setLimit(1)
rel.query()

if (!rel.hasNext()) {
  orphans.push({
    sys_id: sysId,
    name: ci.getValue("name"),
    class: ci.getValue("sys_class_name"),
  })
}

}

return orphans }

Stale CI Detection

// Find CIs not updated by discovery function findStaleCIs(daysOld) { if (typeof daysOld === "undefined") daysOld = 30

var stale = [] var cutoff = new GlideDateTime() cutoff.addDaysLocalTime(-daysOld)

var ci = new GlideRecord("cmdb_ci") ci.addQuery("operational_status", 1) ci.addQuery("last_discovered", "<", cutoff) ci.addNotNullQuery("last_discovered") ci.query()

while (ci.next()) { stale.push({ sys_id: ci.getUniqueValue(), name: ci.getValue("name"), last_discovered: ci.getValue("last_discovered"), }) }

return stale }

MCP Tool Integration

Available CMDB Tools

Tool Purpose

snow_create_ci

Create new CI with proper class

snow_cmdb_search

Search CIs with filters

snow_create_ci_relationship

Create CI relationships

snow_impact_analysis

Analyze CI impact

snow_get_ci_details

Get full CI information

snow_run_discovery

Trigger discovery

Example Workflow

// 1. Search for existing CI await snow_cmdb_search({ ci_class: "cmdb_ci_server", query: "name=PROD-WEB-001", include_relationships: true, })

// 2. Create new CI if not found await snow_create_ci({ ci_class: "cmdb_ci_linux_server", name: "PROD-WEB-002", ip_address: "10.0.1.101", operational_status: 1, })

// 3. Create relationship await snow_create_ci_relationship({ parent: appSysId, child: serverSysId, type: "Runs on::Runs", })

// 4. Impact analysis await snow_impact_analysis({ ci_sys_id: serverSysId, direction: "downstream", depth: 3, })

Best Practices

• Use Correct CI Class - Always use most specific class (cmdb_ci_linux_server, not cmdb_ci)

• Maintain Relationships - CIs without relationships have limited value

• Discovery Alignment - Align manual CIs with discovery patterns

• Operational Status - Keep status current (Operational, Retired, etc.)

• Unique Identifiers - Use serial_number, asset_tag for uniqueness

• Service Mapping - Connect CIs to business services

• Regular Cleanup - Archive retired CIs, remove orphans