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Configuring Units with Multiple Hosts

The HSZ80 Array Controller allows equal but separate access to the targets and units through multiple hosts running on different operating systems, which is called heterogeneous host support. The array controller allows hosts equal access to their targets and units by designating the host mode using the HOST_FUNCTION switch. The controller prevents one host from accessing another host’s units through the use of separate SCSI buses or through the ENABLE_ACCESS_PATH switch.

Host Modes

Each target may have only one host mode assigned to it, making it possible for multiple units to be accessible by one host. This process allows designated targets to talk to their host and vice versa. Host modes allow hosts that implement different SCSI-2 behavior to have equal access to their targets on a shared controller or controller pair.

All hosts are allowed equal access to the controller, but not all hosts implement the same SCSI-2 behavior. This process is achieved by setting a host mode for each target, except when you use the default setting. The default host mode is Host Mode A, which includes DIGITAL UNIX and Open VMS. You only set the host mode on targets if you are using a host operating system that is different than the default.

For targets being accessed by the default host, Host Mode A, you will not need to use the SET controller HOST_FUNCTION switch.

Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide

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Compaq HSZ80 manual Configuring Units with Multiple Hosts, Host Modes