When the main iSCSI portal is unreachable by network failure etc.,
volume attach will fail even if the array has the other portal
addresses alive. To enable nova-compute and brick (with corresponding
patches) to fall-back to alternative portals, this patch makes Cinder
to contains the multiple portal addresses and corresponding IQNs and
LUNs in connection_info returned by initialize_connection API.
The main portal information is also returned in target_portal,
target_iqn, target_lun for backward compatibility. For example:
{"connection_info": {
"driver_volume_type": "iscsi", ...
"data": {"target_portal": "10.0.1.2:3260",
"target_portals": ["10.0.1.2:3260",
"10.0.2.2:3260"],
"target_iqn": "iqn.2014-2.org.example:vol1-1",
"target_iqns":["iqn.2014-2.org.example:vol1-1",
"iqn.2014-2.org.example:vol1-2"],
"target_lun": 1,
"target_luns": [1, 2],
...}}}
This patch makes LVM iSCSI backend return multiple portals,
iqns, and luns when iscsi_secondary_ip_addresses is specified in
cinder.conf.
It also make brick/initiator/connector.py to failover to alternative
paths, if specified, when it fails to establish the main path.
In addition, to unify the data structure, target_portal, target_iqn,
target_lun will also be included even if 'multipath=True' is specified
in connector information.
Change-Id: I55600496487dfaa72301621d1269e50044d9b5dc
Partially Implements: blueprint iscsi-alternative-portal
6d3733beb5