3PAR iSCSI driver allows for multiple iSCSI IPs to be specifed resulting in live-migration failures

[Kurt Martin]

When attempting to do a live-migration on an instance with one or more attached volumes, Nova expects that the IQN will be exactly the same as it's attaching the volume(s) to the new host. This conflicts with the Cinder settings such as "hp3par_iscsi_ips" which allows for multiple IPs for the purpose of load balancing.

An instance on Host A has a volume attached at "/dev/disk/by-path/ip-10.10.220.244:3260-iscsi-iqn.2000-05.com.3pardata:22210002ac002a13-lun-2"
An attempt is made to migrate the instance to Host B.
Cinder sends the request to attach the volume to the new host.
Cinder gives the new host "/dev/disk/by-path/ip-10.10.120.244:3260-iscsi-iqn.2000-05.com.3pardata:22210002ac002a13-lun-2"
Nova looks for the volume on the new host at the old location "/dev/disk/by-path/ip-10.10.220.244:3260-iscsi-iqn.2000-05.com.3pardata:22210002ac002a13-lun-2"

The following error appears in n-cpu in this case:

2015-02-19 17:09:05.574 ERROR nova.virt.libvirt.driver [-] [instance: b6fa616f-4e78-42b1-a747-9d081a4701df] Live Migration failure: Failed to open file '/dev/disk/by-path/ip-10.10.220.244:3260-iscsi-iqn.2000-05.com.3pardata:22210002ac002a13-lun-2': No such file or directory

A nova bug was entered https://bugs.launchpad.net/nova/+bug/1423772 but the 3PAR driver can workaround this limitation by using the same IP in the migration case.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/157879

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/157879
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=72957abe4098abd969dfa775eb5dc6409cde3349
Submitter: Jenkins
Branch: master

commit 72957abe4098abd969dfa775eb5dc6409cde3349
Author: Kurt Martin <email address hidden>
Date: Fri Feb 20 09:19:03 2015 -0800

    Fixed 3PAR driver load balancing during migration

    This patch will not allow the 3PAR iSCSI driver to pick another
    iSCSI IP from the hp3par_iscsi_ips list during a nova live-migration.

    Nova expects that the IQN will be exactly the same as it's attaching
    the volume(s) to the new host during live-migration. This conflicts
    with the Cinder settings such as "hp3par_iscsi_ips" which allows for
    multiple IPs for the purpose of load balancing.

    Change-Id: Idee2fdf7d5bbbe8fb7bdbc3ff20622a213738aa5
    Closes-bug: 1423958