pipeline {
  agent {
    node label: 'master'
  }
  stages {
    stage('Allocate workspace') {
      steps {
        script {
          def extWorkspace = exwsAllocate 'diskpool1'
        }
      }
    }
    stage('Build') {
      steps {
        parallel(
          "a": {
            node(label: 'a') {
              exws (extWorkspace) {
                sh 'ls -la'
              }
            }
          },
          "b": {
            node(label: 'b') {
              exws (extWorkspace) {
                sh 'ls -la'
              }
            }
          }
        )
      }
    }
  }
}