I will be rebooting the host machines which will cause all Linux guests to freeze for about 15-20 minutes that are guests of any given host.

     The 3.19.1 kernel so hugely improved performance over the 2.26.x kernels on the guest machines that it makes sense to get them on the hosts as well.  Because of my wife’s work schedule, tonight is one of the few nights where I have the car and can go do this so tonight it is.

     The 3.19.1 kernel cut the memory usage for a given workload almost in half, made things go faster, and reduced the overall load on the machines I’ve put it on.  The memory usage reduction is most significant as it allows more RAM then to be used as cache so less disk access is required.  Whenever anything is slow, it almost always comes down to waiting on disk I/O.