hi:
    请教个cinder的问题。
    使用本地的lvm做cinder的物理存储。猜测lvm相关的代码在cinder-8.0.0\cinder\volume\drivers\lvm.py里面。
但是没有调用lvm的lvcreate命令:
    def _create_volume(self, name, size, lvm_type, mirror_count, vg=None):
        vg_ref = self.vg
        if vg is not None:
            vg_ref = vg

        vg_ref.create_volume(name, size, lvm_type, mirror_count)

lvcreate是在nova目录下:
[root@opentest stack]# vi ./nova/nova/virt/libvirt/storage/lvm.py
from oslo_concurrency import processutils
from oslo_log import log as logging
from oslo_utils import units
import six

import nova.conf
from nova import exception
from nova.i18n import _
from nova.i18n import _LW
from nova.virt.libvirt import utils

CONF = nova.conf.CONF
LOG = logging.getLogger(__name__)

def create_volume(vg, lv, size, sparse=False):
    """Create LVM image.
    Creates a LVM image with given size.
    :param vg: existing volume group which should hold this image
    :param lv: name for this image (logical volume)
    :size: size of image in bytes
    :sparse: create sparse logical volume
    """
    if sparse:
        preallocated_space = 64 * units.Mi
        check_size(vg, lv, preallocated_space)
        if free_space < size:
            LOG.warning(_LW('Volume group %(vg)s will not be able'
                         ' to hold sparse volume %(lv)s.'
                         ' Virtual volume size is %(size)d bytes,'
                         ' but free space on volume group is'
                         ' only %(free_space)db.'),
                        {'vg': vg,
                         'free_space': free_space,
                         'size': size,
                         'lv': lv})

        cmd = ('lvcreate', '-L', '%db' % preallocated_space,
                '--virtualsize', '%db' % size, '-n', lv, vg)

以及cinder的cinder\brick\local_dev]\lvm.py, brick的代码为什么不放在cinder\volume\drivers\lvm.py里面?
def create_volume(self, name, size_str, lv_type='default', mirror_count=0):
        """Creates a logical volume on the object's VG.

        :param name: Name to use when creating Logical Volume
        :param size_str: Size to use when creating Logical Volume
        :param lv_type: Type of Volume (default or thin)
        :param mirror_count: Use LVM mirroring with specified count

        """

        if lv_type == 'thin':
            pool_path = '%s/%s' % (self.vg_name, self.vg_thin_pool)
            cmd = LVM.LVM_CMD_PREFIX + ['lvcreate', '-T', '-V', size_str, '-n',
                                        name, pool_path]
        else:
            cmd = LVM.LVM_CMD_PREFIX + ['lvcreate', '-n', name, self.vg_name,
                                        '-L', size_str]