On Wed, Sep 23, 2015 at 7:09 AM, Tom van den Berge < tom.vandenbe...@gmail.com> wrote:
> So it seems that Cassandra simply doesn't have enough memory. I'm trying > to understand if this can be caused by the use of vnodes? Is there an > sensible reason why vnodes would consume more memory than regular nodes? Or > does any of you have the same experience? If not, I might be barking up the > wrong tree here, and I would love to know it before upgrading my servers > with more memory. > Yes, range ownership has a RAM/heap cost per-range-owned. This cost is paid during many, but not all, operations. Owning 256 ranges > Owning 1 range. I have not had the same experience but am not at all surprised to hear that vnodes increase heap consumption for otherwise identical configurations. I am surprised to hear that it makes a significant difference in GC time, but you might have been close enough to heap saturation that vnodes tip you over. As an aside, one is likely to win very little net win from vnodes if one's cluster is not now and will never be more than approximately 15 nodes. =Rob
