Creates a disk group

    service_instance
        Service instance to the host or vCenter

    vsan_disk_mgmt_system
        vim.VimClusterVsanVcDiskManagemenetSystem representing the vSan disk
        management system retrieved from the vsan endpoint.

    host_ref
        vim.HostSystem object representing the target host the disk group will
        be created on

    cache_disk
        The vim.HostScsidisk to be used as a cache disk. It must be an ssd disk.

    capacity_disks
        List of vim.HostScsiDisk objects representing of disks to be used as
        capacity disks. Can be either ssd or non-ssd. There must be a minimum
        of 1 capacity disk in the list.

def create_diskgroup(service_instance, vsan_disk_mgmt_system,
                     host_ref, cache_disk, capacity_disks):
    '''
    Creates a disk group

    service_instance
        Service instance to the host or vCenter

    vsan_disk_mgmt_system
        vim.VimClusterVsanVcDiskManagemenetSystem representing the vSan disk
        management system retrieved from the vsan endpoint.

    host_ref
        vim.HostSystem object representing the target host the disk group will
        be created on

    cache_disk
        The vim.HostScsidisk to be used as a cache disk. It must be an ssd disk.

    capacity_disks
        List of vim.HostScsiDisk objects representing of disks to be used as
        capacity disks. Can be either ssd or non-ssd. There must be a minimum
        of 1 capacity disk in the list.
    '''
    hostname = salt.utils.vmware.get_managed_object_name(host_ref)
    cache_disk_id = cache_disk.canonicalName
    log.debug(
        'Creating a new disk group with cache disk \'%s\' on host \'%s\'',
        cache_disk_id, hostname
    )
    log.trace('capacity_disk_ids = %s', [c.canonicalName for c in capacity_disks])
    spec = vim.VimVsanHostDiskMappingCreationSpec()
    spec.cacheDisks = [cache_disk]
    spec.capacityDisks = capacity_disks
    # All capacity disks must be either ssd or non-ssd (mixed disks are not
    # supported)
    spec.creationType = 'allFlash' if getattr(capacity_disks[0], 'ssd') \
            else 'hybrid'
    spec.host = host_ref
    try:
        task = vsan_disk_mgmt_system.InitializeDiskMappings(spec)
    except vim.fault.NoPermission as exc:
        log.exception(exc)
        raise VMwareApiError('Not enough permissions. Required privilege: '
                             '{0}'.format(exc.privilegeId))
    except vim.fault.VimFault as exc:
        log.exception(exc)
        raise VMwareApiError(exc.msg)
    except vmodl.fault.MethodNotFound as exc:
        log.exception(exc)
        raise VMwareRuntimeError('Method \'{0}\' not found'.format(exc.method))
    except vmodl.RuntimeFault as exc:
        log.exception(exc)
        raise VMwareRuntimeError(exc.msg)
    _wait_for_tasks([task], service_instance)
    return True