Yes it is a bug, i have tested on my system. below are the reproducing steps : Precondition: create two instance and attach them with a multiattach volume. there instances id are : c78bdc4b-ebb0-41d2-a435-6f56791a9604, 0efcd163-13ab-4b70-9449-ab89301be1cf 1. delete first attachment : [root@openstackq ~(keystone_admin)]# nova volume-detach c78bdc4b-ebb0-41d2-a435-6f56791a9604 4361ce05-e325-40c3-8b2c-5bcaeedf4260 2. now, delete second attachment : [root@openstackq ~(keystone_admin)]# nova volume-detach 0efcd163-13ab-4b70-9449-ab89301be1cf 4361ce05-e325-40c3-8b2c-5bcaeedf4260 Second step executed without any message. however, if we check output of cinder list, volume's status is shown as a "deattaching". but after few seconds it changes from "deattaching" to "in-use". 3. [root@openstackq ~(keystone_admin)]# cinder list +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | 4361ce05-e325-40c3-8b2c-5bcaeedf4260 | detaching | - | 1 | multiattach | false | 0efcd163-13ab-4b70-9449-ab89301be1cf | | 946009e9-a08f-46d4-88f8-c302d2ec9d75 | in-use | sharedvol | 1 | multiattach | false | 2bf44c23-87b4-4d84-81b6-bc2b1f792d12,c79ad598-be11-490c-8fd0-58c6d72bbe4f | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ [root@openstackq ~(keystone_admin)]# cinder list +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | 4361ce05-e325-40c3-8b2c-5bcaeedf4260 | detaching | - | 1 | multiattach | false | 0efcd163-13ab-4b70-9449-ab89301be1cf | | 946009e9-a08f-46d4-88f8-c302d2ec9d75 | in-use | sharedvol | 1 | multiattach | false | 2bf44c23-87b4-4d84-81b6-bc2b1f792d12,c79ad598-be11-490c-8fd0-58c6d72bbe4f | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ [root@openstackq ~(keystone_admin)]# cinder list +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | 4361ce05-e325-40c3-8b2c-5bcaeedf4260 | detaching | - | 1 | multiattach | false | 0efcd163-13ab-4b70-9449-ab89301be1cf | | 946009e9-a08f-46d4-88f8-c302d2ec9d75 | in-use | sharedvol | 1 | multiattach | false | 2bf44c23-87b4-4d84-81b6-bc2b1f792d12,c79ad598-be11-490c-8fd0-58c6d72bbe4f | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ [root@openstackq ~(keystone_admin)]# cinder list +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | 4361ce05-e325-40c3-8b2c-5bcaeedf4260 | detaching | - | 1 | multiattach | false | 0efcd163-13ab-4b70-9449-ab89301be1cf | | 946009e9-a08f-46d4-88f8-c302d2ec9d75 | in-use | sharedvol | 1 | multiattach | false | 2bf44c23-87b4-4d84-81b6-bc2b1f792d12,c79ad598-be11-490c-8fd0-58c6d72bbe4f | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ [root@openstackq ~(keystone_admin)]# cinder list +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | 4361ce05-e325-40c3-8b2c-5bcaeedf4260 | detaching | - | 1 | multiattach | false | 0efcd163-13ab-4b70-9449-ab89301be1cf | | 946009e9-a08f-46d4-88f8-c302d2ec9d75 | in-use | sharedvol | 1 | multiattach | false | 2bf44c23-87b4-4d84-81b6-bc2b1f792d12,c79ad598-be11-490c-8fd0-58c6d72bbe4f | +--------------------------------------+-----------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ [root@openstackq ~(keystone_admin)]# cinder list +--------------------------------------+--------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+--------+-----------+------+-------------+----------+---------------------------------------------------------------------------+ | 4361ce05-e325-40c3-8b2c-5bcaeedf4260 | in-use | - | 1 | multiattach | false | 0efcd163-13ab-4b70-9449-ab89301be1cf | | 946009e9-a08f-46d4-88f8-c302d2ec9d75 | in-use | sharedvol | 1 | multiattach | false | 2bf44c23-87b4-4d84-81b6-bc2b1f792d12,c79ad598-be11-490c-8fd0-58c6d72bbe4f | +--------------------------------------+--------+-----------+------+-------------+----------+---------------------------------------------------------------------------+