The point I was making was that 10GBe was too expensive (since 10GBe is about on performance-parity with mass storage). With 1 GBe, you're looking at a lot less performance than attached storage. So yes, if your servers are using a regular spinning disk, then this *MIGHT* help the performance a bit since latency may be theoretically better (but throughput will be much lower). However, as the cluster grows, the performance will degrade (latency will get worse since the switch has to process more + bandwidth will decrease since your switch likely can't actually do simultaneous n ports * 1gbe of throughput).
So the point I've been trying to understand is what kind of application would actually benefit from this?
spinning storage in each box, limited amount of RAM, lots of machines, hitting swap occasionally, extremely cost conscious, not performance conscious
So here's two possible alternatives that provide significantly better performance for not much extra cost:
* add more RAM to 1 or more boxes (depending on how much you have in your budget) & make sure heavy workloads only go to those machines.
* if adding more RAM is too expensive use an equivalently-priced SSDs instead of spinning disks - yes you have less storage per-machine, but use a cluster-FS for the data instead (my hunch is that a cluster-FS + SSD for swap will actually get you better performance than spinning disk + RAMster for swap).
* use a growable swap instead of a fixed-size swap? that'll get you more efficient usage of the storage space
Have you actually categorized the performance of RAMster vs spinning disk vs SSD? I think it's useful to see the cost/performance tradeoff in some scenarios. Furthermore, it's important to categorize the cost of RAM vs the cost of the system & what kind of performance you require from the application + what are the specs of the machines in the cluster.
Also, getting back to the central thesis of the article; if it's hitting swap you're looking at a huge performance hit anyways, so why require paying for the "RAM swap" you use when you already do it implicitly performance-wise (i.e. you are already encouraged to use less RAM to improve performance, so charging for the swap use doesn't do anything; if you could lower the RAM usage, you would already be encouraged to do so).