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Multipath Configuration for MSCS with N+1 Configuration (1004440)
Details
There are multiple paths to the shared LUNs on the physical host.
Solution
No multi-pathing software can be running in the physical machine or the virtual machine. The ESX host automatically uses native ESX multi-pathing. For active/passive arrays, both hosts can be connected to only a single storage processor, and there can be only a single path from the physical machine hosting the native node to the array.
When configuring Microsoft Clustering, both nodes in the cluster must see the same views of the storage. RDMs must be presented to the virtual machine in physical compatibility mode. If the RDM were presented to the virtual machine in virtual compatibility mode, ESX introduces a virtual layer and the virtual machine would view the disk differently than the disk presented to the physical machine. This would cause an issue with Microsoft Clustering. The virtual machine must therefore see the RDM as a physical disk with a single path to the storage.
If you enable MPIO software in the virtual machine, it changes the view of the disk on the physical host. As a result, you have a configuration where the virtual machine and the physical host have different views of the storage.
To ensure that the virtual machine and the physical host have the same view of the storage, you must:
Present the RDM in physical compatibility mode to the virtual machine
Not use multipathing software in the physical Windows host
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