CLAYTON@XRT.UPENN.EDU ("Clayton, Paul D.") (05/21/88)
Scott Ballew has asked the following question regarding the use of dual ported disks in a LAVC configuration. > We are looking to purchase some new drives for our uVaxen in a LAVC and > were wondering about the advantages or disadvantages of having them be > dual-ported. Would this allow us to hook them to both of the boot nodes > and to "on the fly" configure them to be on either machine? I know this > sounds academic in a cluster, but what we want is to be able to keep the > cluster flying even if one machine must be down for servicing or what have > you. Any help from people with experience in this or related areas would > be GREATLY appreciated. The VMS 4.X version of the LAVC type cluster does NOT allow for this type of setup for the disks. You can NOT have BOTH the 'A' and 'B' port buttons enabled on a RA type disks which is connected to a UDA/KDA type interface. It is a simple case of one or the other. There is nothing to stop you from setting the allocation class for the two systems connected to 'A' and 'B' to the same value so that the disk can be mounted one way then the other. I do not know if you could mount the disk on a different processor if there are outstanding I/O's on it that went to the 'original' system which had the disk mounted. Something to try in the future, or maybe someone has tried it already? It is rumored that sometime in the realm of VMS 5.x that the failover of UDA/KDA type interfaced disks will be supported and will act just like the HSC controllers. Neat trick!! Hope this helps. pdc Paul D. Clayton Address - CLAYTON%XRT@CIS.UPENN.EDU Disclaimer: All thoughts and statements here are my own and NOT those of my employer, and are also not based on, or contain, restricted information.