terminate instances boot from volume used multipath have residual device

[YaoZheng_ZTE]

Reproducing method as following:
1、nova.conf configure iscsi_used_multipath_tool=multipath， restart nova-compute service
2、launch instance vm1 boot from volume(used HpSan),then attach volume1 for this vm1
3、launch instance vm2 boot from volume(used HpSan),then attach volume2 for this vm2 at the same host
4、terminate vm2
5、vm2 has been destoryed , but /dev/disk/by-path/ device can not be completely removed

[YaoZheng_ZTE (zheng-yao1)]

the reason for this issue :
in /nova/compute/manager.py _shutdown_instance function :
first, query one instances's two volume, then disconnect volume and delete /dev/disk/by-path/ device.
 disconnect the first volume is ok , but the first volume is not removed from san's mapping group, so when disconnect the second volume , in /nova/virt/libvirt/volume.py _disconnect_volume_multipath_iscsi function , can run self._rescan_iscsi() ,because the first volume has not removed san's mapping group yet ,so recsan the first device . so when the vm have destoryed, but the first device is residual .
 Reproducing as following:
1、 launch instance vm1 boot from volume(used HpSan),then attach volume1 for this vm1. /dev/disk/by-path/ as following:
[root@2c514-1-13-SBCJ cinder(keystone_admin)]# ll /dev/disk/by-path/
total 0
lrwxrwxrwx 1 root root 9 Dec 13 18:41 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-0 -> ../../sdb
lrwxrwxrwx 1 root root 9 Dec 13 18:41 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-1 -> ../../sdc
2、 launch instance vm2 boot from volume(used HpSan),then attach volume2 for this vm2. /dev/disk/by-path/ as following:
[root@2c514-1-13-SBCJ cinder(keystone_admin)]# ll /dev/disk/by-path/
total 0
lrwxrwxrwx 1 root root 9 Dec 13 18:41 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-0 -> ../../sdb
lrwxrwxrwx 1 root root 9 Dec 13 18:41 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-1 -> ../../sdc
lrwxrwxrwx 1 root root 9 Dec 13 19:49 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-2 -> ../../sdd
lrwxrwxrwx 1 root root 9 Dec 13 19:49 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-3 -> ../../sde
3、terminat instances vm2, /dev/disk/by-path/ as following:

[root@2c514-1-13-SBCJ cinder(keystone_admin)]# ll /dev/disk/by-path/
total 0
lrwxrwxrwx 1 root root 9 Dec 13 18:41 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-0 -> ../../sdb
lrwxrwxrwx 1 root root 9 Dec 13 18:41 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-1 -> ../../sdc
lrwxrwxrwx 1 root root 9 Dec 13 19:49 ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-2 -> ../../sdd

the device ip-192.14.1.232:3260-iscsi-iqn.2099-01.cn.com.zte:usp.spr-4c:09:b4:b0:02:30-lun-2 should be deleted ,but now cannt be removed

[YaoZheng_ZTE (zheng-yao1)]

Hi melanie witt,
   this issue will be solved by in /nova/virt/libvirt/volume.py function _disconnect_volume_multipath_iscsi , remove call self._rescan_iscsi(). because disconnect volume will not need rescan_iscsi.

[ugvddm (271025598-9)]

this patch: https://review.openstack.org/#/c/184676/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/184676
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=2833f8c08fcfb7961b3c64b285ceff958bf5a05e
Submitter: Jenkins
Branch: master

commit 2833f8c08fcfb7961b3c64b285ceff958bf5a05e
Author: Zhengguang <email address hidden>
Date: Thu May 21 02:31:50 2015 +0000

    remove _rescan_iscsi from disconnect_volume_multipath_iscsi

    terminating instance that attached more than one volume, disconnect
    the first volume is ok, but the first volume is not removed, then
    disconnect the second volume, disconnect_volume_multipath_iscsi
    will call _rescan_iscsi so that rescan the first device, although
    the instance is destroyed, the first device is residual, therefor
    we don't need rescan when disconnect volume.

    Change-Id: I7f2c688aba9e69afaf370b2badc86a2bb3ee899d
    Closes-Bug:#1402535