private void backupAllMembers(final VM managerVM, final int memberCount) {
    managerVM.invoke("backupAllMembers", () -> {
      ManagementService service = managementTestRule.getManagementService();
      DistributedSystemMXBean bean = service.getDistributedSystemMXBean();
      File backupDir = temporaryFolder.newFolder("backupDir");

      DiskBackupStatus status = bean.backupAllMembers(backupDir.getAbsolutePath(), null);

      assertThat(status.getBackedUpDiskStores().keySet().size()).isEqualTo(memberCount);
      assertThat(status.getOfflineDiskStores()).isEmpty(); // TODO: fix GEODE-1946
    });
  }
Takes a back up of all the disk store in a given directory
geode-core/src/distributedTest/java/org/apache/geode/management/DiskManagementDUnitTest.java