Comment 1 for bug 1456480

 he nova also has bad performance during volume detachment when iSCSI multipath is used. I have already opened a bug

https://bugs.launchpad.net/nova/+bug/1454978 and proposed a fix at : https://review.openstack.org/184005
However, I was told that the Nova is going to use os-brick as well.

The logic to determin whether the iSCSI session should be logged out when multipath is used in Nova and Brick is a little different( in _disconnect_volume_multipath_iscsi method of LibvirtISCSIDriver). Seems to me the logic os-brick is better because that the Nova is only check whether a iSCSI portal and iqn is used by the devices that has been attached(assigned) to the VMs in Nova. It didn't check the devices that attached to the host itself for other usage such as used by Cinder for creating volume from image. Whether a iscsi portal and iqn is used shall be