cluster to their new home before the cluster can become full active again. I think I got that right. That means, although you can replace nodes, you can't elastically scale without partitioning work. I am not absolutely clear if that means the re-partitioning work can be done on a live system, or not. I would hope it can. That got me thinking. There are other systems that repartition effectively during operation. Algebraic Multigrids used to solve high Reynolds number Eulerian grids repartition to accelerate the solution phase. I wrote a parallel AMG solver to run on Cray T3Ds in 1995. It was fast, efficient with good conversion rates  but struggled to beat the Cray vectorised versions of the code base on reasonable sized clusters. There is another. A plant. A plant doesn't shutdown when it adds petals to its flower or leaves to its stem it keeps running (so to speak, I havent seen a running flower since University). The plants domain space that its partitioning is sunlight. As it adds leaves doesn't add leaves as a whole ring, but it adds them one by one to make the most use of the available sunlight without shading other spaces. It doesn't require that the cells from one leaf or petal migrate to the new leaf. In essence a plant has achieved the trick of scaling elastically. How does it do this ? There is a biological explanation associated to levels of hormones in the stem which are triggered by light