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vJailbreak

Use vJailbreak Settings

The vjailbreak-settings ConfigMap provides a centralized way to customize and override default settings in the vJailbreak system. This guide shows you how to use this ConfigMap effectively.

Overview

The vjailbreak-settings ConfigMap allows you to:

  • Override system-wide default values
  • Enable or disable optional features
  • Configure global system behaviors
  • Set resource limits and operational parameters

Checking for the ConfigMap

In vJailbreak v0.3.0 and above, the vjailbreak-settings ConfigMap should already exist in your cluster. If it doesn’t exist, you’re likely using an older version and should upgrade to v0.3.0 or above.

To check if the ConfigMap exists:

Terminal window
kubectl get configmap vjailbreak-settings -n migration-system

If you receive an error that the ConfigMap doesn’t exist, please upgrade your vJailbreak installation to the latest version.

Available Settings

The vjailbreak-settings ConfigMap supports the following settings:

SettingDescriptionDefault ValueExample Values
CHANGED_BLOCKS_COPY_ITERATION_THRESHOLDNumber of iterations to copy changed blocks20Any positive integer
VM_ACTIVE_WAIT_INTERVAL_SECONDSInterval to wait for VM to become active (in seconds)20Any positive integer
VM_ACTIVE_WAIT_RETRY_LIMITNumber of retries to wait for VM to become active15Any positive integer
DEFAULT_MIGRATION_METHODDefault method for VM migration (placeholder for future releases, not currently used)hothot (migrate while VM is running), cold (power off VM before migration)
VCENTER_SCAN_CONCURRENCY_LIMITMaximum number of vCenter VMs to scan concurrently10Any positive integer

Modifying Settings

You can modify the ConfigMap to change settings using one of the following methods:

Method 1: Edit with kubectl

Terminal window
kubectl edit configmap vjailbreak-settings -n migration-system

Then add or modify the data values as needed:

apiVersion: v1
kind: ConfigMap
metadata:
  name: vjailbreak-settings
  namespace: migration-system
data:
  CHANGED_BLOCKS_COPY_ITERATION_THRESHOLD: "30"
  VM_ACTIVE_WAIT_INTERVAL_SECONDS: "30"
  VM_ACTIVE_WAIT_RETRY_LIMIT: "20"
  DEFAULT_MIGRATION_METHOD: "hot"
  VCENTER_SCAN_CONCURRENCY_LIMIT: "150"

Method 2: Using kubectl patch

You can modify individual settings without editing the entire ConfigMap:

Terminal window
kubectl patch configmap -n migration-system vjailbreak-settings --type merge -p '{"data":{"VM_ACTIVE_WAIT_INTERVAL_SECONDS":"30","VM_ACTIVE_WAIT_RETRY_LIMIT":"20"}}'

Method 3: From a file

Create a file with your settings:

Terminal window
cat > vjailbreak-settings.yaml << EOF
apiVersion: v1
kind: ConfigMap
metadata:
  name: vjailbreak-settings
  namespace: migration-system
data:
  CHANGED_BLOCKS_COPY_ITERATION_THRESHOLD: "30"
  VM_ACTIVE_WAIT_INTERVAL_SECONDS: "30"
  VM_ACTIVE_WAIT_RETRY_LIMIT: "20"
  DEFAULT_MIGRATION_METHOD: "hot"
  VCENTER_SCAN_CONCURRENCY_LIMIT: "150"
EOF


kubectl apply -f vjailbreak-settings.yaml

Settings in Action

Optimizing Block Copy Operations

To increase the number of iterations for copying changed blocks during hot migrations:

Terminal window
kubectl patch configmap -n migration-system vjailbreak-settings --type merge -p '{"data":{"CHANGED_BLOCKS_COPY_ITERATION_THRESHOLD":"30"}}'

Adjusting VM Activation Parameters

To increase wait time and retry attempts for VM activation:

Terminal window
kubectl patch configmap -n migration-system vjailbreak-settings --type merge -p '{"data":{"VM_ACTIVE_WAIT_INTERVAL_SECONDS":"30","VM_ACTIVE_WAIT_RETRY_LIMIT":"20"}}'

Optimizing Scan Performance

To increase the number of concurrent vCenter scan pods:

Terminal window
kubectl patch configmap -n migration-system vjailbreak-settings --type merge -p '{"data":{"VCENTER_SCAN_CONCURRENCY_LIMIT":"150"}}'

Setting Default Migration Method (Future Feature)

Note: This setting is currently a placeholder and does not affect the system. It will be implemented in future releases.

In upcoming releases, you’ll be able to set the default migration method for VMs. The system supports two migration methods:

  • Hot migration: Migrates VMs while they are running, minimizing downtime but requiring more coordination and potentially multiple sync iterations to capture changed blocks
  • Cold migration: Powers off the VM before migration, ensuring data consistency but causing downtime during the entire migration process

You’ll be able to configure the default method as follows:

Terminal window
kubectl patch configmap -n migration-system vjailbreak-settings --type merge -p '{"data":{"DEFAULT_MIGRATION_METHOD":"cold"}}'

Verification

To verify your settings have been applied correctly:

Terminal window
kubectl get configmap -n migration-system vjailbreak-settings -o yaml

Applying Changes

After modifying settings in the ConfigMap, no restart is required. The ConfigMap is not mounted as a volume; instead, its values are fetched at runtime by the system components.

When Changes Take Effect

The vJailbreak system fetches ConfigMap values as follows:

  • On-demand access: Values are read from the ConfigMap when they are needed for an operation
  • New operations: Changes affect only new operations that start after the ConfigMap is updated
  • In-progress operations: Running operations continue using the values they initially read
  • No caching: The system does not cache these values for extended periods, ensuring relatively quick propagation of changes

Typically, your changes will be effective within seconds for any new operations initiated after updating the ConfigMap.

Best Practices and Considerations

Testing Recommendations

  • Always test configuration changes in a test environment that closely matches your production setup before applying them to production.
  • Validate each setting change independently to understand its impact on system behavior.
  • Document any changes made to default settings for future reference and troubleshooting.

Operational Considerations

  • Setting changes take effect for new operations and do not affect in-progress tasks.
  • The impact of settings varies based on your specific environment (hardware, network, storage configuration).
  • Performance-related settings should be adjusted based on your specific infrastructure capabilities.

Monitoring and Validation

  • After changing settings, monitor system behavior to ensure the changes produce the expected results.
  • Use vJailbreak logs to verify that settings are being correctly applied.

Important: Always select configuration values appropriate for your specific environment. Incorrect settings may negatively impact system performance or stability.