132 Configuration: Disk Groups and Virtual DisksRestricted MappingsMany hosts are able to map up to 256 logical unit numbers (LUNs) (0 to 255)per storage partition. However, the maximum number of mappings differsbecause of operating system variables, failover driver issues, and potentialdata problems. The hosts listed in the table have these mapping restrictions.If you try to map a virtual disk to a LUN that exceeds the restriction on theseoperating systems, the host is unable to access the virtual disk.Guidelines when you work with host types with LUN mapping restrictions:• You cannot change a host adapter port to a restricted host type if there arealready mappings in the storage partition that would exceed the limitimposed by the restricted host type.• Consider the case of the Default Group that has access to LUNs up to 256(0 to 255) and a restricted host type is added to the Default Group. In thiscase, the host that is associated with the restricted host type is able toaccess virtual disks in the Default Group with LUNs within its limits. Forexample, if the Default Group had two virtual disks mapped to LUNs 254and 255, the host with the restricted host type would not be able to accessthose two virtual disks.• If the Default Group has a restricted host type assigned and the storagepartitions are disabled, you can map only a total of 32 LUNs. Anyadditional virtual disks that are created are put in the UnidentifiedMappings area. If additional mappings are defined for one of theseUnidentified Mappings, the Define Additional Mapping dialog shows theLUN list, and the Add button is unavailable.• Do not configure dual mappings on a Windows host.• If there is a host with a restricted host type that is part of a specific storagepartition, all of the hosts in that storage partition are limited to themaximum number of LUNs allowed by the restricted host type.Operating System Highest LUNWindows Server 2003 and Windows server 2008 255Linux 255
