Storage Migration

Hi

I'm looking at doing a storage migration on an ESX 3.5 cluster. Basically moving to a new storage array. My question is, once all the VMs etc have been moved over, whats the best way to remove the old luns/datastores safely? I've see a few articles but most refer to APD states on ESX 4.x and 5.

Do I simply unmount the old datastores from each host then have it removed/un presented by the storage guys? Do I need to remove the VMFS datastore first?

Thanks in advance

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