Many of the challenges could be reduced or mitigated if the pods could be at least partially pressurized to reduce the pressure differential between the inside and out -- but that introduces another complexity -- can the server hardware handle it.
There are quite a few engineering challenges, none of them unsolvable but also none of them seem necessary when it seems the same benefits can be obtained for less effort by keeping the pods above water.
Hosting companies would be either adding capacity (new locations, new land, new construction) or filling existing capacity. Once capacity is full at a location, then what?
The marginal, incremental value of adding a single server once capacity is reached is currently quite high. Using bogus numbers, lets say a location can hold 100,000 servers, then the marginal cost to add the 100,001st server will be very high, and might cost millions. These costs include:
- Cost of planning - when? Which countries? Which locations? Do you serve Kenya out of say South Africa? Or do you need to go to the mountains of Kenya where the air is a more consistent temperature?
- Cost of finding locations - doing deals to get the land for server farms is likely costly.
- Actually buying/leasing the land - how in advance do you do this? Years? Months? Weeks? Leasing land that lays dormant for say 18 months is wasted money.
- Getting approval to put in the required infrastructure (data cables, electricity, redundancy etc)
- Engineering/architectural costs to design buildings each and every time for varying sizes, in different regulatory environments.
- Cost of construction.
- Wasted capacity. There may be a need worldwide for say 50,000 servers, but with multiple continents, that may equate to several locations with 100,000 capacity.
All those costs add up.
Compare that to the marginal cost is adding a standard pod, with a lower server numbers per pod, mass manufactured in one location and shipped to a regulation free spot in the ocean. The marginal cost is not millions to go from (bogus numbers of) 100,000 to 100,001, it is the cost of one additional pod, at a much lower number, e.g. to go from 10,000 to 10,001 costs a fraction of the 100,000 to 100,001 example. The waste is also reduced, as multiple countries/continents can have say an additional X% capacity, added in smaller increments, rather than huge leaps in (initially) wasted capacity.
Now, is that overall cheaper? Maybe, maybe not, who knows? But many large hosting businesses might prefer say a 10% increase in theoretical cost per server added in smaller discrete numbers of servers. Factor in adding capacity in smaller increments with less capacity waste, less need to acquire the rights to land in advance and it might be cheaper in aggregate, even if it is theoretically more expensive per server at currently active locations.
Incidentally, that is the core value proposition of cloud computing like AWS - that you can add capacity incrementally. Despite there being theoretically cheaper options running your own hardware, this is larger capital outlay, with longer turnarounds to add capacity.
Many of the challenges could be reduced or mitigated if the pods could be at least partially pressurized to reduce the pressure differential between the inside and out -- but that introduces another complexity -- can the server hardware handle it.
There are quite a few engineering challenges, none of them unsolvable but also none of them seem necessary when it seems the same benefits can be obtained for less effort by keeping the pods above water.