Dell PowerVault ME4 Series Storage System Administrator’s Guide

Map initiators and volumes

1. Perform one of the following:
   • In the Hosts topic, select the initiators to map and select Action > Map Initiators.
   • In the Volumes topic, select the volumes to map and select Action > Map Volumes.
   • In the Mapping topic, select Action > Map to create a new mapping.
   • In the Mapping topic, select one or more mappings to modify or delete and select Action > Map.
   The Map panel opens and shows two tables side-by-side that list available initiators and volumes. You can use these tables to create mappings. There is also a table underneath the host and volume tables that lists mappings. After you create a mapping and before you save it, the mapping appears in the mappings table and you can modify its settings or delete it.

   The Available Host Groups, Hosts, and Initiators table shows one or more of the following rows:

   Table 1. Available Host Groups, Hosts, and InitiatorsAvailable host groups, hosts, and initiators

   Row description	Group	Host	Nickname	ID
   A row with these values always appears. Select this row to apply map settings to all initiators and create a default mapping.	-	-	(blank)	All Initiators
   A row with these values appears for an initiator that is grouped into a host. Select this row to apply map settings to all initiators in this host.	-	host-name	*	*
   A row with these values appears for an initiator that is grouped into a host group. Select this row to apply map settings to all initiators in this host group.	host-group-name	*	*	*
   A row with these values appears for each initiator. Select this row to apply map settings to this initiator.	- or host-group-name	- or host-name	(blank) or initiator-nickname	initiator-ID

   The Available Volume Groups and Volumes table shows one or more of the following rows:

   Table 2. Available Volume Groups and VolumesAvailable volume groups and volumes

   Row description	Group	Name	Type
   A row with these values appears for a volume/snapshot that is grouped into a volume group. Select this row to apply map settings to all volumes/snapshots in this volume group.	volume-group-name	*	Group
   A row with these values appears for each volume/snapshot. Select this row to apply map settings to this volume/snapshot.	-	volume-name	volume-type

   • If you selected one or more host groups, hosts, or initiators in the Hosts topic, the selected items are displayed in the Available Host Groups, Hosts, and Initiators table, while all available volumes, volume groups, and snapshots are displayed in the Available Volume Groups and Volumes table.
   • If you selected one or more volumes, volume groups, or snapshots in the Volumes topics, the selected items are displayed in the Available Volume Groups and Volumes table, while all available host groups, hosts, or initiators are displayed in the Available Host Groups, Hosts, and Initiators table.
   • If you opened the Map panel from the Mapping topic without selecting a mapping, the Available Host Groups, Hosts, and Initiators and Available Volume Groups and Volumes tables are fully populated with all available items.
   • If you selected a mapping from the mapping table in the Mapping topic, the mapping appears in mapping table at the bottom of the panel and the Available Host Groups, Hosts, and Initiators and Available Volume Groups and Volumes tables are fully populated.
2. Perform one of the following:
   • If you started in the Hosts topic, select the volumes to map to the initiators and click the Map button.
     NOTE:If you attempt to map a volume to a host group that is already mapped to an initiator and one or more volumes, the mapping might fail with the error The specified LUN overlaps a previously defined LUN. The workaround to this issue is to unmap the existing volumes that are mapped to the host group, then map the volume that failed to map to the host group, and remap the unmapped volumes to the host group.
   • If you started in the Volumes topic, select initiators to map to those volumes and click the Map button.
   • If you started in the Mapping topic and did not select any mappings, select one or more initiators and one or more volumes to map and click the Map button. When the Map button is clicked, the button changes from Map to Reset.
   • If you started in the Mapping topic and one or more existing mappings was selected, the mappings appear in the Map panel. When mappings are selected from the Mapping topic, the Reset button is be displayed instead of a Map button.

     For each initiator mapped to a volume, a row appears in the mapping table at the bottom of the panel. The mapping mode, LUN, or ports of each mapping can be modified or a mapping can be deleted.

3. Perform any of the following:
   • To remove a new mapping, select Remove Row from the Action column.
   • To edit a mapping, set the following options:
     • Mode - The access mode can specify read-write access, read-only access, or no access to a volume. The default is read-write. When a mapping specifies no access, the volume is masked, which means it is not visible to associated initiators. Masking is useful to override an existing default map that allows open access so that access is denied only to specific initiators. To allow access to specific hosts and deny access to all other hosts, create explicit maps to those hosts. For example, an engineering volume could be mapped with read-write access for the engineering server and read-only access for servers used by other departments.
     • LUN - The LUN identifies the volume to a host. The default is the lowest available LUN. Both controllers share one set of LUNs, and any unused LUN can be assigned to a mapping. However, each LUN is generally only used once as a default LUN. For example, if LUN 5 is the default for Volume1, no other volume in the storage system can use LUN 5 on the same port as its default LUN. For explicit mappings, the rules differ: LUNs used in default mappings can be reused in explicit mappings for other volumes and other hosts.
       NOTE:When mapping a volume to a host with the Linux ext3 file system, specify read-write access. Otherwise, the file system will be unable to mount the volume and will report an error such as “unknown partition table.”
     • Ports - Port selections specify controller host ports through which initiators are permitted to access, or are prevented from accessing, the volume. Selecting a port number automatically selects the corresponding port in each controller.
   • To clear the mapping table, click Reset.
   • To save a new mapping or save changes to an existing mapping, select Save from the Action column.
   • To undo changes to an existing mapping, select Revert from the Actions columns.
   • To delete an existing mapping, select Delete from the Action column.
4. Once the list is correct, to apply changes, click Apply or OK.
   A confirmation panel appears.
5. Click Yes to continue. Otherwise, click No. If you clicked Yes, the mapping changes are saved.
6. To close the panel, click Close.