A host object is a logical object that represents a list of worldwide port names (WWPNs) and a list of iSCSI names that identify the interfaces that the host system uses to communicate with the Lenovo Storage V7000 system. Fibre Channel and SAS connections use WWPNs to identify the host interfaces to the systems. iSCSI names can be either iSCSI qualified names (IQNs) or extended unique identifiers (EUIs).
A typical configuration has one host object for each host system that is attached to the system. If a cluster of hosts accesses the same storage, you can add host bus adapter (HBA) ports from several hosts to one host object to make a simpler configuration. A host object can have both WWPNs and iSCSI names.
The system does not automatically present volumes to the host system. You must map each volume to a particular host object to enable the volume to be accessed through the WWPNs or iSCSI names that are associated with the host object. For Fibre Channel-attached hosts, the system reports the node login count, which is the number of nodes that can detect each WWPN. If the count is less than expected for the current configuration, you might have a connectivity problem. For iSCSI-attached hosts, the number of logged-in nodes refers to iSCSI sessions that are created between hosts and nodes, and might be greater than the current number of nodes on the system.
When you create a new Fibre Channel host object, the system presents a list of candidate WWPNs that have logged into the system but are not yet configured in host objects. Some Fibre Channel HBA device drivers do not leave their ports logged in if no disks are detected on the fabric, so they are not visible in the list of candidate ports. You must enter the WWPNs for such hosts manually. There is no equivalent list of candidate IQNs available when creating iSCSI hosts. All iSCSI host port IQNs must be entered manually.
The system can detect only WWPNs that have connected to the system through the Fibre Channel network or through any IP network. Some Fibre Channel HBA device drivers do not leave ports logged in if no disks are detected on the fabric or IP network. The configuration interface provides a method to manually type the port names.
A WWPN or iSCSI name can be added to only one host object.
You can use the port-mask property of the host object to control the Fibre Channel ports on each Lenovo Storage V7000node that a host can access. The port mask applies to logins from the WWPNs that are associated with the host object. The port-mask configuration has no effect on iSCSI connections.
For each login between a host Fibre Channel port and node Fibre Channel port, the node examines the port mask for the associated host object and determines if access is allowed or denied. If access is denied, the node responds to SCSI commands as if the HBA WWPN is unknown.
The port mask is 64 bits. Valid mask values range from all 0s (no ports enabled) to all 1s (all ports enabled). For example, a mask of 0011 enables port 1 and port 2. The default value is all 1s.
When you create a host mapping to a host, the host ports that are associated with the host object can view the LUN that represents the volume on many ports. Nodes follow the American National Standards Institute (ANSI) Fibre Channel (FC) standards for SCSI LUs that are accessed through multiple node ports. All nodes within a single I/O group present a consistent set of SCSI LUs across all ports on those nodes.