I carried out an assessment on the ROI/TCO for a VDI solution some months ago. Any scenario i worked out, i did not get a positive ROI. here's a gist of how i arrived at the ROI.
ROI = current cost - VDI cost
1. Cost of the Desktop / laptop hardware
2. Cost of spares
3. support costs
1. Cost of thin client
2. Cost of server (6 - 8 VMs per CPU core)
3. Storage cost
4. Rack cost
5. Network Switch cost
6. Deployment cost
7. Virtualization software license cost
1. Difference in hardware cost (Desktop cost MINUS (server hardware+rack+switch+storage+license+deployment+thin client))
2. Management cost (managing VDIs will be cheaper)
3. Energy savings (Desktop energy consumption MINUS energy consumption of(Server+Thin client+switch+storage)
ROI is always negative as the hardware acquisition costs goes up significantly.
With the ever falling prices of Desktops & laptops, i don't think Desktop virtualization will gain momentum any soon.
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