6V0-22.25 Troubleshooting and Repairing

Troubleshooting and Repairing Detailed Explanation

SDDC Manager Workflow and Task Failures

Exam Radar

• Core Priority: Examining the underlying task engine and Java-based service logs when automated workflows fail.

• High Frequency: Inspecting the vcf-operations-manager.log to identify specific stage error codes.

• Confusion Alert: Differentiating between an in-progress task that needs a manual database cleanup versus a restartable workflow.

• Scenario Logic: Utilizing psql utilities to query the SDDC Manager inventory for mismatched states.

• Version Delta: Using the SDDC Manager API to clear stuck tasks and return the system to a known good state.

Atomic Deconstruction

• Actionable: Navigate to /var/log/vmware/vcf/sddc-manager/vcf-operations-manager.log to trace the execution history of a failed host commissioning or domain creation task.

• Parametric: Query the SDDC Manager inventory database using psql to identify resources stuck in a "PENDING" or "IN_PROGRESS" state.

• Causal: Identifying the specific stage of failure within a workflow allows for targeted remediation, preventing the need for a full system rollback.

SKILLS.md Matrix

Target	Log/Tool	Troubleshooting Focus
Workflows	vcf-operations-manager.log	Stage-specific error codes
Inventory	psql Utility	Mismatched resource states
API	SDDC Manager API	Task cleanup and restart logic

Host Commissioning and Connectivity Issues

Exam Radar

• Core Priority: Resolving failures during the initial integration of physical hosts into the SDDC.

• High Frequency: Troubleshooting SSH connectivity failures due to expired certificates or public key mismatches.

• Scenario Logic: Using esxcli and ping with the "Do Not Fragment" bit to detect VLAN or MTU (Jumbo Frame) mismatches.

• Version Delta: Validating host prerequisites such as clean partition tables and compatible hypervisor versions via Cloud Builder logs.

Atomic Deconstruction

• Actionable: Run esxcli network ip netstack to verify that the management and vMotion stacks are correctly configured on the target host.

• Parametric: Perform an MTU test using ping -d -s 8972 to confirm the network can support the Jumbo Frames required for vSAN and Overlay traffic.

• Causal: Mismatched MTU settings across the physical switch and virtual switch lead to silent packet loss, which frequently causes host commissioning to hang or fail.

SKILLS.md Matrix

Element	Logic	Atomic Detail
Connectivity	SSH/Public Key	Management plane access verification
Network	MTU/VLAN	Jumbo Frame and tagging validation
Prerequisites	Partition Table	Disk cleanup and hypervisor alignment

vSAN Health and Data Availability Remediation

Exam Radar

• Core Priority: Deconstructing health service alerts to prevent data loss or unavailability in hyper-converged clusters.

• High Frequency: Identifying "Reduced Availability" states using esxcli vsan debug object list.

• Scenario Logic: Resolving hardware compatibility or disk balance alerts within the vSphere Client.

• Version Delta: Procedures for replacing failed NVMe or SSD drives while maintaining active data redundancy.

Atomic Deconstruction

• Actionable: Use the vSphere Client Health Service to identify specific disk groups or physical disks reporting "Network Congestion" or "Hardware Failure".

• Parametric: Initiate a manual resynchronization for vSAN objects that have fallen out of compliance with their assigned storage policy.

• Causal: Prompt replacement of failed physical disks prevents a single-node failure from escalating into a cluster-wide data unavailability event.

SKILLS.md Matrix

Category	Atomic Requirement	Operational Detail
Health Alert	vSAN Health Service	Disk balance and compatibility checks
Debugging	esxcli vsan debug	Object-level repair and status
Recovery	Disk Replacement	Maintaining redundancy during hardware swap

NSX-T Logical Routing and Overlay Connectivity

Exam Radar

• Core Priority: Isolating the Geneve encapsulation layer from the logical routing layer to resolve "silent packet loss".

• High Frequency: Verifying Tunnel Endpoint (TEP) connectivity using specific diagnostic commands.

• Confusion Alert: Distinguishing between a Distributed Firewall (DFW) drop and a physical switch MTU configuration error.

• Scenario Logic: Utilizing Traceflow to visually map packet paths through logical switches and Tier-0/Tier-1 gateways.

• Version Delta: Troubleshooting BGP peering failures with physical Top-of-Rack (ToR) switches, focusing on AS numbers and MD5 mismatches.

Atomic Deconstruction

• Actionable: Run esxcli network diag ping to verify VTEP-to-VTEP connectivity and identify potential MTU or VLAN tagging issues.

• Parametric: Execute a Traceflow analysis from the NSX Manager to identify the exact logical component or firewall rule dropping a packet.

• Causal: Failure in TEP communication typically stems from a physical network that does not support the 1600+ byte MTU required for overlay encapsulation.

SKILLS.md Matrix

Element	Tool	Troubleshooting Logic
Overlay	TEP Diagnostics	VTEP-to-VTEP ping and MTU check
Logical Path	Traceflow	Identifying drops in routing/firewall
BGP Peering	Routing Table Audit	AS number and MD5 password verification

NSX Edge Cluster and Service Failures

Exam Radar

• Core Priority: Ensuring the health of Edge nodes for North-South traffic and centralized services like NAT or Load Balancing.

• High Frequency: Using get functional-state on the Edge CLI to verify routing and management service status.

• Scenario Logic: Analyzing syslog entries to determine triggers for Active/Standby failover, such as keepalive timeouts.

• Version Delta: Identifying packet drops caused by datapath buffer exhaustion during sudden traffic spikes.

Atomic Deconstruction

• Actionable: Log in to the Edge CLI and execute get dataplane stats to check for high CPU utilization on specific cores or packet drops.

• Parametric: Review /var/log/syslog on the Edge node to investigate physical link flaps or heartbeat failures that triggered a service migration.

• Causal: A crash in the datapath process on an Edge node will immediately halt North-South traffic, necessitating a failover to the Standby node.

SKILLS.md Matrix

Target	Command	Diagnostic Goal
Service State	get functional-state	Management and Routing service health
Data Plane	get dataplane stats	CPU core usage and buffer drops
Logs	/var/log/syslog	Root cause of failover events

Avi Controller and Cloud Connector Connectivity

Exam Radar

• Core Priority: Maintaining the management heartbeat between the Avi Controller and vCenter/NSX-T.

• High Frequency: Identifying "Yellow" or "Red" cloud states in the Avi UI caused by API timeouts or authentication failures.

• Confusion Alert: Differentiating between an SE failing to reach the Controller versus a Cloud Connector failing to reach the infrastructure API.

• Scenario Logic: Troubleshooting SE discovery issues where new Service Engines do not appear in the inventory.

• Version Delta: Investigating Java exceptions in the portal-webapp.log for management plane errors.

Atomic Deconstruction

• Actionable: Generate a tech-support bundle from the Controller CLI to analyze the cloud-connector.log for infrastructure communication errors.

• Parametric: Verify that Service Engines can reach the Controller’s management IP over ports 443 and 8443 to complete the discovery process.

• Causal: An invalid SSL certificate or expired credentials for the vCenter/NSX service account will break the Cloud Connector, preventing any new SE scaling.

SKILLS.md Matrix

Component	Logic	Troubleshooting Detail
Cloud Link	Cloud Status Tab	API connectivity and auth health
Logs	cloud-connector.log	Deep dive into infrastructure API errors
Discovery	Ports 443/8443	SE-to-Controller communication path

Service Engine Data Plane and Traffic Failures

Exam Radar

• Core Priority: Resolving issues where the Service Engine is active but failing to pass application traffic.

• High Frequency: Utilizing built-in packet capture utilities to identify TCP handshake failures or RST packets.

• Confusion Alert: Distinguishing between a backend server reset and a Service Engine dropping packets due to resource exhaustion.

• Scenario Logic: Troubleshooting MAC address and ARP resolution issues in complex VLAN or Gratuitous ARP environments.

• Version Delta: Monitoring internal SE resource usage for "CPU Hog" processes that cause packet drops.

Atomic Deconstruction

• Actionable: Perform a real-time packet capture through the Avi UI for a specific Virtual Service to observe the traffic flow between the client, SE, and backend.

• Parametric: Verify that the Service Engine has correctly resolved the ARP entries for its default gateway and all backend pool members.

• Causal: High CPU utilization on an SE's dispatcher core often leads to packet drops, indicating a need for horizontal scale-out or resource reservation adjustments.

SKILLS.md Matrix

Target	Tool	Troubleshooting Goal
Packet Flow	UI Packet Capture	Identifying TCP/SSL handshake resets
Layer 2	ARP Table Audit	Verification of gateway and member MACs
SE Health	Resource Monitor	Detecting CPU hogging or memory leaks

Virtual Service Health and Backend Pool Issues

Exam Radar

• Core Priority: Deconstructing the Virtual Service health score to find the specific point of failure.

• High Frequency: Debugging backend servers marked "Down" by checking for HTTP 4xx/5xx errors or incorrect "Expect" strings.

• Scenario Logic: Identifying pool member "flapping" caused by aggressive monitor timers or network congestion.

• Version Delta: Troubleshooting connection multiplexing failures where the backend limits connections from the SE's SNIP.

Atomic Deconstruction

• Actionable: Inspect the health monitor logs for a "Down" pool member to see the exact response received from the application (e.g., status code or timeout).

• Parametric: Adjust health monitor intervals and thresholds to prevent false positives during periods of transient network latency.

• Causal: If a backend server limits concurrent connections from the SE IP, the application may experience queuing and increased latency even if the server is "Up".

SKILLS.md Matrix

Element	Logic	Atomic Detail
Health Score	4 Pillars Analysis	Performance, Resource, Anomaly, Security
Monitoring	Monitor Debugging	Expect string and status code validation
Performance	Connection Queuing	Backend limit vs. SE SNIP concurrency

Root Cause Analysis via Analytics and Logs

Exam Radar

• Core Priority: Using the Avi analytics engine for post-mortem analysis of failed requests.

• High Frequency: Using end-to-end timing metrics to determine if latency is in the network, the SE, or the server.

• Confusion Alert: Identifying if a 503 error was generated by the Avi SE (no servers) or passed through from the backend.

• Scenario Logic: Analyzing WAF logs to identify and remediate false positives that are blocking legitimate traffic.

• Version Delta: Utilizing Significant Log forensics to filter for specific response codes during troubleshooting windows.

Atomic Deconstruction

• Actionable: Review the "Client-to-Avi" and "Avi-to-Server" timing breakdown to isolate whether latency is occurring on the WAN or the internal LAN.

• Parametric: Filter logs for 503 Service Unavailable errors and check the "Significance" field to see if any pool members were available during the request.

• Causal: WAF false positives can be remediated by creating specific exclusion rules for security signatures that are incorrectly flagging valid application traffic.

SKILLS.md Matrix

Category	Atomic Requirement	Operational Detail
Forensics	End-to-End Timing	Network vs. App server latency split
Error Analysis	Log Filtering	Distinguishing local vs. remote errors
Security	WAF Log Review	Signature exclusion and rule tuning

SDDC Manager Database and Services Remediation

Exam Radar

• Core Priority: Restoring functionality when the SDDC Manager's internal services or database become inconsistent.

• High Frequency: Restarting the "vcf-operations-manager" service to resolve unresponsive UI or API issues.

• Confusion Alert: Distinguishing between a service-level failure and a Postgres database corruption.

• Scenario Logic: Manually updating the database state of a decommissioned host that remains in the inventory.

• Version Delta: Utilizing the sos (Supportability and Operations Strategy) tool to gather diagnostic data for VMware support.

Atomic Deconstruction

• Actionable: Use the systemctl restart command on the SDDC Manager appliance to recycle the operations manager and inventory services.

• Parametric: Check the health of the PostgreSQL database by verifying the service status and disk space on the /storage/db partition.

• Causal: Inconsistent database records regarding host status will prevent new workload domain creation, requiring manual SQL entry correction to match physical reality.

SKILLS.md Matrix

Target	Action	Tool/Command
Service Health	Restart UI/API	systemctl restart vcf-operations-manager
DB Integrity	Query Status	psql -h localhost -U vcf
Support	Log Collection	sos --log-collect

Backup Restoration and Recovery Workflows

Exam Radar

• Core Priority: Recovering the management plane from catastrophic failure using file-based backups.

• High Frequency: Restoring the Avi Controller configuration JSON to a fresh cluster to recover virtual services.

• Scenario Logic: Identifying the correct sequence to restore vCenter and NSX Managers to ensure environment synchronization.

• Version Delta: Using SDDC Manager to restore the inventory state from an external SFTP/FTP backup repository.

Atomic Deconstruction

• Actionable: Deploy a new Avi Controller node and use the "Restore Configuration" feature to upload the latest JSON backup file.

• Parametric: Verify that the SFTP backup server for SDDC Manager is reachable and contains valid daily configuration exports.

• Causal: Restoring a stale backup of the NSX Manager can result in a mismatch with the actual state of the Edge nodes, requiring manual data plane synchronization.

SKILLS.md Matrix

Component	Recovery Method	Key Artifact
Avi Controller	JSON Import	Config Backup File
SDDC Manager	SFTP Restore	Inventory DB Backup
NSX-T	Manager Restore	Management Plane Snapshot

Post-Repair Validation and Health Re-certification

Exam Radar

• Core Priority: Confirming that remediation actions have successfully returned the system to an operational state.

• High Frequency: Running the "Global Pre-check" in SDDC Manager post-repair to ensure no residual errors remain.

• Scenario Logic: Verifying that Service Engines have re-established heartbeats with the Controller after a management network repair.

• Version Delta: Re-syncing the Cloud Connector to ensure the infrastructure inventory (vCenter/NSX) is up to date.

Atomic Deconstruction

• Actionable: Trigger a manual inventory refresh in the Avi Controller to confirm that all segments, T1s, and pools are correctly discovered post-repair.

• Parametric: Verify the "Elastic HA" status of Service Engine Groups to ensure the system can once again scale out in response to traffic.

• Causal: A successful "Green" health score in the Avi UI indicates that the data plane, management plane, and backend health monitors are all synchronized.

SKILLS.md Matrix

Category	Atomic Requirement	Operational Detail
Verification	SDDC Pre-check	System-wide health certification
Resiliency	HA Status Check	Confirming scale-out capability
Integration	Cloud Sync	Refreshing infrastructure object discovery