LUN Numbering Consistency
When mapping the same virtual volume to multiple application servers, in certain situations, it is important to maintain LUN numbering consistency across multiple application servers. For instance, one such case is when mapping to ESX servers.
When a virtual volume is mapped, SANmelody software will attempt to match the first mapped LUN on all subsequent mappings to multiple application servers. To facilitate this process, follow the guidelines below. It is important to be aware that SANmelody software will NOT change existing mappings if the matching LUN is not available for new mappings. In this case, a message will appear on the screen warning that the LUN must be changed manually.
To keep LUNs consistent when the same virtual volume is mapped to multiple application servers, follow these guidelines:
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The best practice to follow, if possible, is to begin with no mappings to the application servers. Then, make and complete all the mappings for one virtual volume at a time, before making any mappings for the next virtual volume. In this manner, the LUN selected by the initial mapping of a particular virtual volume will be available on the other application servers for subsequent multiple mappings.
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If it is not possible to follow the best practice in step 1 because there are previous mappings to application servers occupying LUNs, then the first mapping you make should be to the application server which has the most LUNs already used. In this case, the initial LUN for that virtual volume will be high enough to be available on all other application servers.
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You can also make the initial mapping for a virtual volume and then change it manually to a LUN that you know will be available on the other application servers before making the additional mappings. All additional mappings of a virtual volume will attempt to use the same LUN as the initial mapping.
Refer to Mapping Properties for instructions on changing assigned LUNs.