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HP OpenVMS Systemsask the wizard |
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The Question is: Is it possible to cluster two AlphaServer 2000 with DSSI and SCSI busses used for cluster interconnect ? Both busses must be active in the cluster for data's migration. thank you. The Answer is : Yes. In an OpenVMS Cluster, you can configure as many interconnects as you like (and as your hardware will permit). There is one central requirement when configuring interconnects for an OpenVMS Cluster: each node within the cluster must be able to directly communicate with every other node in the cluster. These intracluster communications can occur via any SCS-capable communications interconnect. This requirement is also known as the "OpenVMS Cluster Rule of Total Connectivity". To meet the rule of total connectivity, most cluster configurations will use a broadcast connection such as CI, Ethernet, or FDDI. This is the easiest to configure and to explain, but configurations with the correct organization of multiple cluster interconnects can also be used to meet the rule. The two most common interconnects used within clusters that are NOT capable of host-to-host SCS communications are storage interconnects. The two most common storage interconnects are SCSI and any KFQSA-based connection to a DSSI bus. (DSSI connections via adapters other than the KFQSA can be used for host-to-host communications.) These are storage interconnects, and do not permit host-to-host communications. As an example of using multiple interconnects to meet the rule of total connectivity: various configurations with DSSI daisy-chains are also possible. Three hosts, each with two DSSI controllers, can be organized into a triangular configuration, with each of the two DSSI controllers present on each host connected to one of the adjacent hosts. In other words, there are a total of three DSSI buses, and each DSSI bus has two hosts and zero or more storage devices or adapters connected to it. (Most sites will also use an Ethernet or FDDI interconnect in this and in other configurations.)
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