Product of (Maximum number of nodes that can drain in parallel) and (Highest total VM memory request allocations across nodes)
- Documentation
- Red Hat OpenShift service on AWS
- Virtualization
- Live migration
- About live migration history bug_report picture_as_pdf
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- About
- What's new
- Introduction to ROSA
- Architecture
- Tutorials
- Tutorials overview
- ROSA with HCP activation and account linking
- ROSA with HCP private offer acceptance and sharing
- Verifying Permissions for a ROSA STS Deployment
- Deploying ROSA with a Custom DNS Resolver
- Using AWS WAF and Amazon CloudFront to protect ROSA workloads
- Using AWS WAF and AWS ALBs to protect ROSA workloads
- Deploying OpenShift API for Data Protection on a ROSA cluster
- AWS Load Balancer Operator on ROSA
- Configuring Microsoft Entra ID (formerly Azure Active Directory) as an identity provider
- Using AWS Secrets Manager CSI on ROSA with STS
- Using AWS Controllers for Kubernetes on ROSA
- Deploying the External DNS Operator on ROSA
- Dynamically issuing certificates using the cert-manager Operator on ROSA
- Assigning consistent egress IP for external traffic
- Updating component routes with custom domains and TLS certificates
- Getting started with ROSA
- Deploying an application
- Getting started
- Prepare your environment
- Install ROSA with HCP clusters
- Creating ROSA with HCP clusters using the default options
- Creating a ROSA cluster using Terraform
- Creating ROSA with HCP clusters using a custom AWS KMS encryption key
- Creating a private cluster on ROSA with HCP
- Creating ROSA with HCP clusters with external authentication
- Creating ROSA with HCP clusters without a CNI plugin
- Deleting a ROSA with HCP cluster
- Install ROSA Classic clusters
- Creating a ROSA cluster with STS using the default options
- Creating a ROSA cluster with STS using customizations
- Creating a ROSA (classic architecture) cluster using Terraform
- Interactive cluster creation mode reference
- Creating an AWS PrivateLink cluster on ROSA
- Configuring a shared virtual private cloud for ROSA clusters
- Accessing a ROSA cluster
- Configuring identity providers using Red Hat OpenShift Cluster Manager
- Revoking access to a ROSA cluster
- Deleting a ROSA cluster
- Deploying ROSA without AWS STS
- AWS prerequisites for ROSA
- Understanding the ROSA deployment workflow
- Required AWS service quotas
- Configuring your AWS account
- Installing the ROSA CLI
- Creating a ROSA cluster without AWS STS
- Configuring a private cluster
- Deleting access to a ROSA cluster
- Deleting a ROSA cluster
- Command quick reference for creating clusters and users
- Support
- Support overview
- Managing your cluster resources
- Approved Access
- Getting support
- Remote health monitoring with connected clusters
- Gathering data about your cluster
- Summarizing cluster specifications
- Troubleshooting
- Troubleshooting ROSA installations
- Troubleshooting networking
- Verifying node health
- Troubleshooting Operator issues
- Investigating pod issues
- Troubleshooting storage issues
- Investigating monitoring issues
- Diagnosing OpenShift CLI (oc) issues
- Troubleshooting expired offline access tokens
- Troubleshooting IAM roles
- Troubleshooting cluster deployments
- Red Hat OpenShift service on AWS managed resources
- Web console
- CLI tools
- Red Hat OpenShift Cluster Manager
- Cluster administration
- Security and compliance
- Authentication and authorization
- Authentication and authorization overview
- Understanding authentication
- Managing user-owned OAuth access tokens
- Configuring identity providers
- Using RBAC to define and apply permissions
- Understanding and creating service accounts
- Using service accounts in applications
- Using a service account as an OAuth client
- Assuming an AWS IAM role for a service account
- Scoping tokens
- Using bound service account tokens
- Managing security context constraints
- Understanding and managing pod security admission
- Syncing LDAP groups
- Upgrading
- CI/CD
- Images
- Overview of images
- Overview of the Cluster Samples Operator
- Using the Cluster Samples Operator with an alternate registry
- Creating images
- Managing images
- Managing image streams
- Using image streams with Kubernetes resources
- Triggering updates on image stream changes
- Image configuration resources (Classic)
- Image configuration resources (HCP)
- Using templates
- Using Ruby on Rails
- Using images
- Add-on services
- Storage
- Registry
- Operators
- Operators overview
- Understanding Operators
- User tasks
- Administrator tasks
- Developing Operators
- About the Operator SDK
- Installing the Operator SDK CLI
- Go-based Operators
- Ansible-based Operators
- Helm-based Operators
- Defining cluster service versions (CSVs)
- Working with bundle images
- Complying with pod security admission
- Validating Operators using the scorecard
- Validating Operator bundles
- High-availability or single-node cluster detection and support
- Configuring built-in monitoring with Prometheus
- Configuring leader election
- Object pruning utility
- Migrating package manifest projects to bundle format
- Operator SDK CLI reference
- Migrating to Operator SDK v0.1.0
- Networking
- Building applications
- Building applications overview
- Projects
- Creating applications
- Viewing application composition using the Topology view
- Working with Helm charts
- Deployments
- Quotas
- Using config maps with applications
- Monitoring project and application metrics using the Developer perspective
- Monitoring application health
- Editing applications
- Working with quotas
- Pruning objects to reclaim resources
- Idling applications
- Deleting applications
- Using the Red Hat Marketplace
- Backing up and restoring applications
- Nodes
- Overview of nodes
- Working with pods
- Automatically scaling pods with the Custom Metrics Autoscaler Operator
- Release notes
- Custom Metrics Autoscaler Operator overview
- Installing the custom metrics autoscaler
- Understanding the custom metrics autoscaler triggers
- Understanding the custom metrics autoscaler trigger authentications
- Pausing the custom metrics autoscaler
- Gathering audit logs
- Gathering debugging data
- Viewing Operator metrics
- Understanding how to add custom metrics autoscalers
- Removing the Custom Metrics Autoscaler Operator
- Controlling pod placement onto nodes (scheduling)
- About pod placement using the scheduler
- Placing pods relative to other pods using pod affinity and anti-affinity rules
- Controlling pod placement on nodes using node affinity rules
- Placing pods onto overcommited nodes
- Placing pods on specific nodes using node selectors
- Controlling pod placement using pod topology spread constraints
- Using jobs and daemon sets
- Working with nodes
- Working with containers
- Understanding containers
- Using Init Containers to perform tasks before a pod is deployed
- Using volumes to persist container data
- Mapping volumes using projected volumes
- Allowing containers to consume API objects
- Copying files to or from a container
- Executing remote commands in a container
- Using port forwarding to access applications in a container
- Working with clusters
- Observability
- Observability overview
- Monitoring
- Monitoring overview
- Accessing monitoring for user-defined projects
- Configuring the monitoring stack
- Disabling monitoring for user-defined projects
- Enabling alert routing for user-defined projects
- Managing metrics
- Managing alerts
- Reviewing monitoring dashboards
- Accessing third-party monitoring APIs
- Troubleshooting monitoring issues
- Config map reference for the Cluster Monitoring Operator
- Logging
- Release notes
- Support
- Troubleshooting logging
- About Logging
- Installing Logging
- Updating Logging
- Visualizing logs
- Configuring your Logging deployment
- Log collection and forwarding
- Log storage
- Logging alerts
- Performance and reliability tuning
- Scheduling resources
- Uninstalling Logging
- Exported fields
- API reference
- Glossary
- service Mesh
- service Mesh 2.x
- About OpenShift service Mesh
- service Mesh 2.x release notes
- service Mesh architecture
- service Mesh deployment models
- service Mesh and Istio differences
- Preparing to install service Mesh
- Installing the Operators
- Creating the serviceMeshControlPlane
- Adding workloads to a service mesh
- Enabling sidecar injection
- Upgrading service Mesh
- Managing users and profiles
- Security
- Traffic management
- Metrics, logs, and traces
- Performance and scalability
- Deploying to production
- Federation
- Extensions
- 3scale WebAssembly for 2.1
- 3scale Istio adapter for 2.0
- Troubleshooting service Mesh
- Control plane configuration reference
- Kiali configuration reference
- Jaeger configuration reference
- Uninstalling service Mesh
- service Mesh 2.x
- Serverless
- Virtualization
- About
- Getting started
- Installing
- Post-installation configuration
- Updating
- Virtual machines
- Creating VMs from Red Hat images
- Creating VMs from custom images
- Connecting to VM consoles
- Configuring SSH access to VMs
- Editing virtual machines
- Editing boot order
- Deleting virtual machines
- Exporting virtual machines
- Managing virtual machine instances
- Controlling virtual machine states
- Using virtual Trusted Platform Module devices
- Managing virtual machines with OpenShift Pipelines
- Advanced virtual machine management
- Working with resource quotas for virtual machines
- Specifying nodes for virtual machines
- Configuring certificate rotation
- Configuring the default CPU model
- UEFI mode for virtual machines
- Configuring PXE booting for virtual machines
- Scheduling virtual machines
- About high availability for virtual machines
- Control plane tuning
- VM disks
- Networking
- Networking configuration overview
- Connecting a VM to the default pod network
- Exposing a VM by using a service
- Connecting a VM to an OVN-Kubernetes secondary network
- Connecting a VM to a service mesh
- Configuring a dedicated network for live migration
- Configuring and viewing IP addresses
- Managing MAC address pools for network interfaces
- Storage
- Storage configuration overview
- Configuring storage profiles
- Managing automatic boot source updates
- Reserving PVC space for file system overhead
- Configuring local storage by using HPP
- Enabling user permissions to clone data volumes across namespaces
- Configuring CDI to override CPU and memory quotas
- Preparing CDI scratch space
- Using preallocation for data volumes
- Managing data volume annotations
- Live migration
- Nodes
- Monitoring
- Support
- Backup and restore
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About live migration
Live migration is the process of moving a running virtual machine (VM) to another node in the cluster without interrupting the virtual workload. Live migration enables smooth transitions during cluster upgrades or any time a node needs to be drained for maintenance or configuration changes.
By default, live migration traffic is encrypted using Transport Layer Security (TLS).
Live migration requirements
Live migration has the following requirements:
-
The cluster must have shared storage with
ReadWriteMany(RWX) access mode. -
The cluster must have sufficient RAM and network bandwidth.
You must ensure that there is enough memory request capacity in the cluster to support node drains that result in live migrations. You can determine the approximate required spare memory by using the following calculation:
The default number of migrations that can run in parallel in the cluster is 5.
-
If a VM uses a host model CPU, the nodes must support the CPU.
-
Configuring a dedicated Multus network for live migration is highly recommended. A dedicated network minimizes the effects of network saturation on tenant workloads during migration.
VM migration tuning
You can adjust your cluster-wide live migration settings based on the type of workload and migration scenario. This enables you to control how many VMs migrate at the same time, the network bandwidth you want to use for each migration, and how long OpenShift Virtualization attempts to complete the migration before canceling the process. Configure these settings in the HyperConverged custom resource (CR).
If you are migrating multiple VMs per node at the same time, set a bandwidthPerMigration limit to prevent a large or busy VM from using a large portion of the node’s network bandwidth. By default, the bandwidthPerMigration value is 0, which means unlimited.
A large VM running a heavy workload (for example, database processing), with higher memory dirty rates, requires a higher bandwidth to complete the migration.
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Post copy mode, when enabled, triggers if the initial pre-copy phase does not complete within the defined timeout. During post copy, the VM CPUs pause on the source host while transferring the minimum required memory pages. Then the VM CPUs activate on the destination host, and the remaining memory pages transfer into the destination node at runtime. This can impact performance during the transfer. Post copy mode should not be used for critical data, or with unstable networks. |
Common live migration tasks
You can perform the following live migration tasks:
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Monitor the progress of all live migrations in the Migration tab of the OpenShift Virtualization web console.
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View VM migration metrics in the Metrics tab of the web console.