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The Question is: In "Guidelines for OpenVMS Cluster Configurations" appendix D2 you state "For maximum performance and availability, use two disjoint FDDI LANs, each with dedicated host adapters and full-duplex FDDI intersite links connected to GIGAswitch/FDDI bridges at each site. " For the last years I have successfully used such configurations to provide high availability and high performance 3 and 4 site clusters. One of the components used by our applications is the host based shadowing in order to provide full disaster redundancy Now I am being told by Enterrasys that they will stop provide the GigaSwitches at the end of this year. My questions: 1) Is there a prefered path from Compaq concerning the technology used for designing multpile site OpenVMS Clusters ? 2) What technology and implementations are Compaq using when you qualifying multiple site OpenVMS Clusters ? 3) Do you have any guidlines for calculating site recovery for multiple site OpenVMS Clusters ? Thanks in advance. The Answer is : Host-based shadowing and the various other mechanisms and packages that are used within an OpenVMS Cluster are not particularly specific to the underlying physical media involved. The particular network media used and the associated mechanisms are of rather less interest than are the basic clustering latency and bandwidth requirements, and meeting the disparate physical media routing and the required level of redundancy of the physical media. Once the basic latency and bandwidth requirements are met (eg: 10 megabit Ethernet; the site-specific requirements will likely require greater bandwidth), you will be looking at avoiding a single-point failure (such as having the redundant inter-site network links routed via non-adjacent conduit, and having multiple redundant network switches or network bridges.) ATM, Gigabit Ethernet and Fibre Channel are the most common approaches for remote access in current clustering configurations. In addition to the clustering information included in the two manuals in the OpenVMS manual set, disaster-tolerant clustering information is also available as part of the Disaster Tolerant Cluster Services (DTCS) services offering.
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