NetBackup™ Deployment Guide for Kubernetes Clusters

Last Published:
Product(s): NetBackup & Alta Data Protection (10.4.0.1)
  1. Introduction
    1.  
      About Cloud Scale deployment
    2.  
      About NetBackup Snapshot Manager
    3.  
      About MSDP Scaleout
    4.  
      Required terminology
    5.  
      User roles and permissions
  2. Section I. Configurations
    1. Prerequisites
      1.  
        Preparing the environment for NetBackup installation on Kubernetes cluster
      2.  
        Prerequisites for MSDP Scaleout and Snapshot Manager (AKS/EKS)
      3. Prerequistes for Kubernetes cluster configuration
        1.  
          Config-Checker utility
        2.  
          Data-Migration for AKS
        3.  
          Webhooks validation for EKS
      4. Prerequisites for Cloud Scale configuration
        1.  
          Cluster specific settings
        2.  
          Cloud specific settings
      5.  
        Prerequisites for deploying environment operators
    2. Recommendations and Limitations
      1.  
        Recommendations of NetBackup deployment on Kubernetes cluster
      2.  
        Limitations of NetBackup deployment on Kubernetes cluster
      3.  
        Limitations in MSDP Scaleout
    3. Configurations
      1.  
        Contents of the TAR file
      2.  
        Initial configurations
      3.  
        Configuring the environment.yaml file
      4. Loading docker images
        1.  
          Installing the docker images for NetBackup
        2.  
          Installing the docker images for Snapshot Manager
        3.  
          Installing the docker images and binaries for MSDP Scaleout
      5.  
        Configuring NetBackup IT Analytics for NetBackup deployment
      6. Configuring NetBackup
        1. Primary and media server CR
          1.  
            After installing primary server CR
          2.  
            After Installing the media server CR
        2.  
          Elastic media server
    4. Configuration of key parameters in Cloud Scale deployments
      1.  
        Tuning touch files
      2.  
        Setting maximum jobs
      3.  
        Enabling intelligent catalog archiving
      4.  
        Enabling security settings
      5.  
        Configuring email server
      6.  
        Reducing catalog storage management
      7.  
        Configuring zone redundancy
      8.  
        Enabling client-side deduplication capabilities
  3. Section II. Deployment
    1. Deploying operators
      1.  
        Deploying the operators
    2. Deploying Postgres
      1.  
        Deploying Postgres
      2.  
        Enable request logging, update configuration, and copying files from/to PostgreSQL pod
    3. Deploying Cloud Scale
      1.  
        Installing Cloud Scale
    4. Deploying MSDP Scaleout
      1. MSDP Scaleout configuration
        1.  
          Initializing the MSDP operator
        2.  
          Configuring MSDP Scaleout
        3.  
          Configuring the MSDP cloud in MSDP Scaleout
        4.  
          Using MSDP Scaleout as a single storage pool in NetBackup
        5.  
          Using S3 service in MSDP Scaleout
        6.  
          Enabling MSDP S3 service after MSDP Scaleout is deployed
      2.  
        Deploying MSDP Scaleout
    5. Verifying Cloud Scale deployment
      1.  
        Verifying Cloud Scale deployment
  4. Section III. Monitoring and Management
    1. Monitoring NetBackup
      1.  
        Monitoring the application health
      2.  
        Telemetry reporting
      3.  
        About NetBackup operator logs
      4.  
        Monitoring Primary/Media server CRs
      5.  
        Expanding storage volumes
      6. Allocating static PV for Primary and Media pods
        1.  
          Recommendation for media server volume expansion
        2.  
          (AKS-specific) Allocating static PV for Primary and Media pods
        3.  
          (EKS-specific) Allocating static PV for Primary and Media pods
    2. Monitoring Snapshot Manager
      1.  
        Overview
      2.  
        Logs of Snapshot Manager
      3.  
        Configuration parameters
    3. Monitoring MSDP Scaleout
      1.  
        About MSDP Scaleout status and events
      2.  
        Monitoring with Amazon CloudWatch
      3.  
        Monitoring with Azure Container insights
      4.  
        The Kubernetes resources for MSDP Scaleout and MSDP operator
    4. Managing NetBackup
      1.  
        Managing NetBackup deployment using VxUpdate
      2.  
        Updating the Primary/Media server CRs
      3.  
        Migrating the cloud node for primary or media servers
    5. Managing the Load Balancer service
      1.  
        About the Load Balancer service
      2.  
        Notes for Load Balancer service
      3.  
        Opening the ports from the Load Balancer service
    6. Managing PostrgreSQL DBaaS
      1.  
        Changing database server password in DBaaS
      2.  
        Updating database certificate in DBaaS
    7. Performing catalog backup and recovery
      1.  
        Backing up a catalog
      2. Restoring a catalog
        1.  
          Primary server corrupted
        2.  
          MSDP-X corrupted
        3.  
          MSDP-X and Primary server corrupted
    8. Managing MSDP Scaleout
      1.  
        Adding MSDP engines
      2.  
        Adding data volumes
      3. Expanding existing data or catalog volumes
        1.  
          Manual storage expansion
      4.  
        MSDP Scaleout scaling recommendations
      5. MSDP Cloud backup and disaster recovery
        1.  
          About the reserved storage space
        2. Cloud LSU disaster recovery
          1.  
            Recovering MSDP S3 IAM configurations from cloud LSU
      6.  
        MSDP multi-domain support
      7.  
        Configuring Auto Image Replication
      8. About MSDP Scaleout logging and troubleshooting
        1.  
          Collecting the logs and the inspection information
  5. Section IV. Maintenance
    1. MSDP Scaleout Maintenance
      1.  
        Pausing the MSDP Scaleout operator for maintenance
      2.  
        Logging in to the pods
      3.  
        Reinstalling MSDP Scaleout operator
      4.  
        Migrating the MSDP Scaleout to another node pool
    2. PostgreSQL DBaaS Maintenance
      1.  
        Configuring maintenance window for PostgreSQL database in AWS
      2.  
        Setting up alarms for PostgreSQL DBaaS instance
    3. Patching mechanism for Primary and Media servers
      1.  
        Overview
      2.  
        Patching of containers
    4. Upgrading
      1.  
        Upgrading Cloud Scale deployment for Postgres using Helm charts
      2. Upgrading NetBackup individual components
        1.  
          Upgrading NetBackup operator
        2. Upgrading NetBackup application
          1.  
            Upgrade NetBackup from previous versions
          2.  
            Procedure to rollback when upgrade of NetBackup fails
        3.  
          Upgrading MSDP Scaleout
        4. Upgrading Snapshot Manager
          1.  
            Post-migration tasks
    5. Cloud Scale Disaster Recovery
      1.  
        Cluster backup
      2.  
        Environment backup
      3.  
        Cluster recovery
      4.  
        Cloud Scale recovery
      5.  
        Environment Disaster Recovery
      6.  
        DBaaS Disaster Recovery
    6. Uninstalling
      1.  
        Uninstalling NetBackup environment and the operators
      2.  
        Uninstalling Postgres using Helm charts
      3.  
        Uninstalling Snapshot Manager from Kubernetes cluster
      4. Uninstalling MSDP Scalout from Kubernetes cluster
        1.  
          Cleaning up MSDP Scaleout
        2.  
          Cleaning up the MSDP Scaleout operator
    7. Troubleshooting
      1. Troubleshooting AKS and EKS issues
        1.  
          View the list of operator resources
        2.  
          View the list of product resources
        3.  
          View operator logs
        4.  
          View primary logs
        5.  
          Socket connection failure
        6.  
          Resolving an issue where external IP address is not assigned to a NetBackup server's load balancer services
        7.  
          Resolving the issue where the NetBackup server pod is not scheduled for long time
        8.  
          Resolving an issue where the Storage class does not exist
        9.  
          Resolving an issue where the primary server or media server deployment does not proceed
        10.  
          Resolving an issue of failed probes
        11.  
          Resolving token issues
        12.  
          Resolving an issue related to insufficient storage
        13.  
          Resolving an issue related to invalid nodepool
        14.  
          Resolving a token expiry issue
        15.  
          Resolve an issue related to KMS database
        16.  
          Resolve an issue related to pulling an image from the container registry
        17.  
          Resolving an issue related to recovery of data
        18.  
          Check primary server status
        19.  
          Pod status field shows as pending
        20.  
          Ensure that the container is running the patched image
        21.  
          Getting EEB information from an image, a running container, or persistent data
        22.  
          Resolving the certificate error issue in NetBackup operator pod logs
        23.  
          Pod restart failure due to liveness probe time-out
        24.  
          NetBackup messaging queue broker take more time to start
        25.  
          Host mapping conflict in NetBackup
        26.  
          Issue with capacity licensing reporting which takes longer time
        27.  
          Local connection is getting treated as insecure connection
        28.  
          Primary pod is in pending state for a long duration
        29.  
          Backing up data from Primary server's /mnt/nbdata/ directory fails with primary server as a client
        30.  
          Storage server not supporting Instant Access capability on Web UI after upgrading NetBackup
        31.  
          Taint, Toleration, and Node affinity related issues in cpServer
        32.  
          Operations performed on cpServer in environment.yaml file are not reflected
        33.  
          Elastic media server related issues
        34.  
          Failed to register Snapshot Manager with NetBackup
        35.  
          Post Kubernetes cluster restart, flexsnap-listener pod went into CrashLoopBackoff state or pods were unable to connect to flexsnap-rabbitmq
        36.  
          Post Kubernetes cluster restart, issues observed in case of containerized Postgres deployment
      2. Troubleshooting AKS-specific issues
        1.  
          Data migration unsuccessful even after changing the storage class through the storage yaml file
        2.  
          Host validation failed on the target host
        3.  
          Primary pod goes in non-ready state
      3. Troubleshooting EKS-specific issues
        1.  
          Resolving the primary server connection issue
        2.  
          NetBackup Snapshot Manager deployment on EKS fails
        3.  
          Wrong EFS ID is provided in environment.yaml file
        4.  
          Primary pod is in ContainerCreating state
        5.  
          Webhook displays an error for PV not found
  6. Appendix A. CR template
    1.  
      Secret
    2. MSDP Scaleout CR
      1.  
        MSDP Scaleout CR template for AKS
      2.  
        MSDP Scaleout CR template for EKS

Upgrading Cloud Scale deployment for Postgres using Helm charts

Before upgrading Cloud Scale deployment for Postgres using Helm charts, ensure that:

  • Helm charts for operators and Postgres are available from a public or private registry.

  • Images for operators, and Cloud Scale services are available form a public or private registry.

Note:

During the upgrade process, ensure that the cluster nodes are not scaled down to 0 or restarted.

To upgrade operators

  1. Run the following script when upgrading from an earlier release of Cloud Scale that used a single helm chart or the kustomize deployment method:

    scripts/prep_operators_for_upgrade.sh

  2. Use the following command to suspend the backup job processing:

    nbpemreq -suspend_scheduling

  3. Perform the following steps to upgrade the operators:
    • Use the following command to save the operators chart values to a file:

      # helm show values operators-<version>.tgz > operators-values.yaml

    • Use the following command to edit the chart values to match your deployment scenario:

      # vi operators-values.yaml

    • Execute the following command to upgrade the operators:

      helm upgrade --install operators operators-<version>.tgz -f operators-values.yaml -n netbackup-operator-system

      Or

      If using the OCI registry, use the following command:

      helm upgrade --install operators oci://abcd.veritas.com:5000/helm-charts/operators --version <version> -f operators-values.yaml -n netbackup-operator-system

    Following is an example for operators-values.yaml file:

    # Copyright (c) 2023 Veritas Technologies LLC. All rights reserved
     
    # Default values for operators.
    # This is a YAML-formatted file.
    # Declare variables to be passed into your templates.
     
    global:
      # Toggle for platform-specific features & settings
      # Microsoft AKS: "aks"
      # Amazon EKS: "eks"
      platform: "eks"
      # This specifies a container registry that the cluster has access to.
      # NetBackup images should be pushed to this registry prior to applying this
      # Environment resource.
      # Example Azure Container Registry name:
      # example.azurecr.io
      # Example AWS Elastic Container Registry name:
      # 123456789012.dkr.ecr.us-east-1.amazonaws.com
      containerRegistry: "364956537575.dkr.ecr.us-east-1.amazonaws.com/ECR Name"
      operatorNamespace: "netbackup-operator-system"
     
      storage:
        eks:
          fileSystemId: fs-0f3cc640eeec507d0
     
    msdp-operator:
      image:
        name: msdp-operator
        # Provide tag value in quotes eg: '17.0'
        tag: "20.4"
        pullPolicy: Always
     
      namespace:
        labels:
          control-plane: controller-manager
     
      # This determines the path used for storing core files in the case of a crash.
      corePattern: "/core/core.%e.%p.%t"
     
      # This specifies the number of replicas of the msdp-operator controllers
      # to create. Minimum number of supported replicas is 1.
      replicas: 2
      # Optional: provide label selectors to dictate pod scheduling on nodes.
      # By default, when given an empty {} all nodes will be equally eligible.
      # Labels should be given as key-value pairs, ex:
      #   agentpool: mypoolname
      nodeSelector: {}
     
      # Storage specification to be used by underlying persistent volumes.
      # References entries in global.storage by default, but can be replaced
      storageClass:
        name: nb-disk-premium
        size: 5Gi
     
      # Specify how much of each resource a container needs.
      resources:
        # Requests are used to decide which node(s) should be scheduled for pods.
        # Pods may use more resources than specified with requests.
        requests:
          cpu: 150m
          memory: 150Mi
        # Optional: Limits can be implemented to control the maximum utilization by pods.
        # The runtime prevents the container from using more than the configured resource limits.
        limits: {}
     
      logging:
        # Enable verbose logging
        debug: false
        # Maximum age (in days) to retain log files, 1 <= N <= 365
        age: 28
        # Maximum number of log files to retain, 1 <= N =< 20
        num: 20
     
    nb-operator:
      image:
        name: "netbackup/operator"
        tag: "10.4"
        pullPolicy: Always
     
      # nb-operator needs to know the version of msdp and flexsnap operators for webhook
      # to do version checking
      msdp-operator:
        image:
          tag: "20.4"
     
      flexsnap-operator:
        image:
          tag: "10.4.0.0.1016"
     
      namespace:
        labels:
          nb-control-plane: nb-controller-manager
     
      nodeSelector:
        node_selector_key: agentpool
        node_selector_value: agentpool
     
      #loglevel:
      #  "-1" - Debug (not recommended for production)
      #  "0"  - Info
      #  "1"  - Warn
      #  "2"  - Error
     
      loglevel:
        value: "0"
     
    flexsnap-operator:
      replicas: 1
     
      namespace:
        labels: {}
     
      image:
        name: "veritas/flexsnap-deploy"
        tag: "10.4.0.1004"
        pullPolicy: Always
     
      nodeSelector:
        node_selector_key: agentpool
        node_selector_value: agentpool

To upgrade Cloud Scale deployment

  1. Run the following command as a workaround for deploying the trust manager:

    helm repo add jetstack https://charts.jetstack.io --force-update kubectl create namespace trust-manager helm upgrade -i -n trust-manager trust-manager jetstack/trust-manager --set app.trust.namespace=netbackup --version v0.7.0 --wait

  2. Upload the new images to your private registry.

    Note:

    Skip this step when using Veritas registry.

  3. Use the following command to suspend the backup job processing:

    nbpemreq -suspend_scheduling

  4. Perform the following steps when installing the PostgreSQL database.

    Note:

    This step is not applicable when using DBaaS.

    • Use the following command to save the PostgreSQL chart values to a file:

      # helm show values postgresql-<version>.tgz > postgres-values.yaml

    • Use the following command to edit the chart values:

      vi postgres-values.yaml

    • Execute the following command to upgrade the PostgreSQL database:

      # helm upgrade --install postgresql postgresql-<version>.tgz -f postgres-values.yaml -n netbackup

      Or

      If using the OCI registry, use the following command:

      helm upgrade --install postgresql oci://abcd.veritas.com:5000/helm-charts/netbackup-postgresql --version <version> -f postgres-values.yaml -n netbackup

    Following is an example for postgres-values.yaml file:

    # Copyright (c) 2024 Veritas Technologies LLC. All rights reserved
     
    # Default values for postgresql.
    global:
      environmentNamespace: "netbackup"
      containerRegistry: "364956537575.dkr.ecr.us-east-1.amazonaws.com"
      
    postgresql:
      replicas: 1
      # The values in the image (name, tag) are placeholders. These will be set
      # when the deploy_nb_cloudscale.sh runs.
      image:
        name: "netbackup/postgresql"
        tag: "14.11.1.0"
        pullPolicy: Always
      service:
        serviceName: nb-postgresql
      volume:
        volumeClaimName: nb-psql-pvc
        volumeDefaultMode: 0640
        pvcStorage: 5Gi
        # configMapName: nbpsqlconf
        storageClassName: nb-disk-premium
        mountPathData: /netbackup/postgresqldb
        secretMountPath: /netbackup/postgresql/keys/server
        # mountConf: /netbackup
        timezone: null
      securityContext:
        runAsUser: 0
      createCerts: true
      # pgbouncerIniPath: /netbackup/pgbouncer.ini
      serverSecretName: postgresql-server-crt
      clientSecretName: postgresql-client-crt
      dbSecretName: dbsecret
      dbPort: 13785
      pgbouncerPort: 13787
      dbAdminName: postgres
      initialDbAdminPassword: postgres
      dataDir: /netbackup/postgresqldb
      # postgresqlConfFilePath: /netbackup/postgresql.conf
      # pgHbaConfFilePath: /netbackup/pg_hba.conf
      defaultPostgresqlHostName: nb-postgresql
    To save $$ you can set storageClassName to nb-disk-standardssd for non-production environments.

    Note:

    For Postgres pod not to be scheduled on any other nodes other than primary nodepool, then add Kubernetes taints to the Media, MSDP and flexsnap/Snapshot Manager nodepool.

    If primary node pool has taints applied, then you manually add tolerations to the PostgreSQL StatefulSet as follows:

    • To verify that node pools use taints, run the following command:

      kubectl get nodes -o=custom-columns=NodeName:.metadata.name,TaintKey:.spec.taints[*].key,TaintValue:.spec.taints[*].value,TaintEffect:.spec.taints[*].effect

      NodeName TaintKey TaintValue TaintEffect
      ip-10-248-231-149.ec2.internal <none> <none> <none>
      ip-10-248-231-245.ec2.internal <none> <none> <none>
      ip-10-248-91-105.ec2.internal nbupool agentpool NoSchedule
    • To view StatefulSets, run the following command:

      kubectl get statefulsets -n netbackup

      NAME READY AGE
      nb-postgresql 1/1 76m
      nb-primary 0/1 51m
    • Edit the PostgreSQL StatefulSets and add tolerations as follows:

      kubectl edit statefulset nb-postgresql -n netbackup

    Following is an example of the modified PostgreSQL StatefulSets:

    apiVersion: apps/v1
    kind: StatefulSet
    metadata:
      annotations:
        meta.helm.sh/release-name: postgresql
        meta.helm.sh/release-namespace: netbackup
      creationTimestamp: "2024-03-25T15:11:59Z"
      generation: 1
      labels:
        app: nb-postgresql
        app.kubernetes.io/managed-by: Helm
      name: nb-postgresql
    ...
    spec:
      template:
        spec:
          containers:
          ...
     
     
          nodeSelector:
            nbupool: agentool
          tolerations:
          - effect: NoSchedule
            key: nbupool
            operator: Equal
            value: agentpool
  5. Perform the following to create Secret containing DBaaS CA certificates:

    Note:

    This step is not applicable when using containerized Postgres.

    • For AWS:

      TLS_FILE_NAME='/tmp/tls.crt'
      PROXY_FILE_NAME='/tmp/proxy.pem'
       
      rm -f ${TLS_FILE_NAME} ${PROXY_FILE_NAME}
       
      DB_CERT_URL="https://truststore.pki.rds.amazonaws.com/global/global-bundle.pem"
      DB_PROXY_CERT_URL="https://www.amazontrust.com/repository/AmazonRootCA1.pem"
       
      curl ${DB_CERT_URL} --output ${TLS_FILE_NAME}
      curl ${DB_PROXY_CERT_URL} --output ${PROXY_FILE_NAME}
       
      cat ${PROXY_FILE_NAME} >> ${TLS_FILE_NAME}
       
      kubectl -n netbackup create secret generic postgresql-netbackup-ca --from-file ${TLS_FILE_NAME}
    • For Azure:

      TLS_FILE_NAME='/tmp/tls.crt'
       
      rm -f ${TLS_FILE_NAME}
       
      DB_CERT_URL="https://cacerts.digicert.com/DigiCertGlobalRootCA.crt.pem"
       
      curl ${DB_CERT_URL} --output ${TLS_FILE_NAME}
       
      kubectl -n netbackup create secret generic postgresql-netbackup-ca --from-file ${TLS_FILE_NAME}
  6. Create db cert bundle as follows:

    Note:

    This step must be performed when using containerized Postgres.

    cat <<EOF | kubectl apply -f -
    apiVersion: trust.cert-manager.io/v1alpha1
    kind: Bundle
    metadata:
      name: db-cert
    spec:
      sources:
      - secret:
          name: "postgresql-netbackup-ca"
          key: "tls.crt"
      target:
        namespaceSelector:
          matchLabels:
            kubernetes.io/metadata.name: "$ENVIRONMENT_NAMESPACE"
        configMap:
          key: "dbcertpem"
    EOF

    After installing db-cert bundle, ensure that you have db-cert configMap present in netbackup namespace with size 1 as follows:

    bash-5.1$ kubectl get configmap db-cert -n $ENVIRONMENT_NAMESPACE
    NAME      DATA   AGE
    db-cert   1      11h

    Note:

    If the configMap is showing the size as 0, then delete it and ensure that the trust-manager recreates it before proceeding further.

  7. Perform the following steps to upgrade the Cloud Scale deployment:
    • Use the following command to obtain the environment name:

      $ kubectl get environments -n $ENVIRONMENT_NAMESPACE

    • Navigate to the directory containing the patch file and upgrade the Cloud Scale deployment as follows:

      $ cd scripts/

      $ kubectl patch environment <env-name> --type json -n $ENVIRONMENT_NAMESPACE --patch-file cloudscale_patch.json

    Modify the patch file if your current environment CR specifies spec.primary.tag or spec.media.tag. The patch file listed below assumes the default deployment scenario where only spec.tag and spec.msdpScaleouts.tag are listed.

    Note:

    When upgrading from embedded Postgres to containerized Postgres, add dbSecretName to the patch file.

    Examples of .json files:

    • For containerized_cloudscale_patch.json:

      [
        {
          "op": "replace",
          "path": "/spec/dbSecretName",
          "value": "dbsecret"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/tag" ,
          "value" : "10.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/msdpScaleouts/0/tag" ,
          "value" : "20.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/cpServer/0/tag" ,
          "value" : "10.4.0.1074"
        }
      ]
    • For containerized_cloudscale_patch.json with primary, media tags and global tag:

      [
        {
          "op": "replace",
          "path": "/spec/dbSecretName",
          "value": "dbsecret"
        }, 
        {
          "op" : "replace" ,
          "path" : "/spec/primary/tag" ,
          "value" : "10.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/mediaServers/0/tag" ,
          "value" : "10.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/msdpScaleouts/0/tag" ,
          "value" : "20.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/cpServer/0/tag" ,
          "value" : "10.4.0.1074"
        }
      ]
    • For DBAAS_cloudscale_patch.json:

      Note:

      This patch file is to be used only during DBaaS to DBaaS migration.

      [
        {
          "op" : "replace" ,
          "path" : "/spec/dbSecretProviderClass" ,
          "value" : "dbsecret-spc"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/tag" ,
          "value" : "10.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/msdpScaleouts/0/tag" ,
          "value" : "20.4"
        },
        {
          "op" : "replace" ,
          "path" : "/spec/cpServer/0/tag" ,
          "value" : "10.4.0.1101"
        }
      ]
  8. Wait until Environment CR displays the status as ready. During this time pods are expected to restart and any new services to start.

    Run the following command to check the environment CR status:

    - kubectl get environment -n "namespace"

    For example,

    kubectl  get environment -n netbackup
    NAME                READY   AGE   STATUS
    anshannewtesttrtm   4/4     57m   Success
  9. Resume the backup job processing by using the following command:

    # nbpemreq -resume_scheduling