Variable cylinder engine operation

[lonestar48]

During the operation of internal combustion engines that have variable cylinder use. are the same cylinders in use all the time creating uneven wear or do they use different cylinders each time. And what are the cylinders not in use doing, are they open to exhaust.

[Clanad]

Almost all of the current crop of VCM engines, the cylinders that are deactivated are the same cylinders each time. The exhaust and intake valves are stopped in the closed position so as to stop the air pumping in the engine.
As to uneven wear... if you stop to think about it, the pistons are still moving within the cylinders, whether they are the ones deactivated or not, so there would no issued with uneven wear.