Author : Ivanka Radkova
Topic Name : Add a VMDK Affinity Rule
Publication Name : vSphere Virtual Machine Administration
Product/Version : VMware vSphere/7.0
Does the VMDK Affinity rule impact just VMDK files or all VM files - specifically vmx.
Every VM has a "home" directory which contains config files such as VMX.
The rules you're asking about are for when you have multiple sets of VMDK files for a single VM.
What are you actually looking to achieve?
The "VMDK Affinity rule" is a feature of a Datastore Cluster. By default and the general rule of thumb is to hold all files together in one directory which is the $Home_Dir of the VM. But if you have multiple vDisk or larger vDisk and run out of free space on a Datastore/LUN you can allow the sDRS to spread them on several Datastores within the Datastore Cluster.
To answer your Question... it works only for VMDKs and not *.vmx, *.log, swap or the other files of a VM.