I think the value of the r6gd (assuming cpu is good compared to intel) is more cpu, not disk. I'm not running on spark the cassandra servers, and having more cpu cores in my cluster will sure help. It all depends on the workloads, some workloads need more io, some cpu.
i3 servers are great servers, they are currently our servers in production, be it i3.4xlarge in one env, or i3.2xlarge in another, but the thing is we want to use less servers, and sadly there isn't a i3en.4xlarge server, so I started to look for other options. Take your example, 10.7k for 32cores and 256gb memory vs 3.9k for 8cores and 60gb , you can clearly see you pay less for each core and each gb of memory. Why do you see I will only use part of the power? My bottleneck today is cpu, the more writes I have the more cpu my servers use. All assuming Arm will give me good performance, but that's another discussion. Regarding moving some of the data to EBS, the plan is using symbolic links for a specific set of tables, I've done it in the past, it's not ideal, but if it will allow me to save a lot of money by using a different server class, I would do it. On Mon, Mar 1, 2021 at 11:20 PM Erick Ramirez <erick.rami...@datastax.com> wrote: > it's not the same, notice I wrote r6gd, these are the ones with nvme, i'm >> looking just at those. >> > > I'm aware. I did use r6gd.2xlarge in my example. :) > > >> I do not need all the space that i3en gives me (and probably won't be >> able to use it all due to memory usage, or have other issues just like you >> mention), so the plan is use the big enough r6gd nodes, such as >> r6gd.8xlarge, it has 1.9tb nvme, it should good enough for my needs >> > > I feel like we have a disconnect here. :) You won't get value from the > r6gd.8xlarge. You're paying for 32 cores + 256GB RAM which are mostly > unusable to you unless you have a configuration where Spark is co-located > with C* on the servers. It's the equivalent of using a truck to transport 2 > boxes when a car will suffice. > > From a dollar perspective, you're opting to pay $10,714/yr for > a r6gd.8xlarge (I arbitrarily picked a standard 1-year term in West coast) > versus $3839/year for an i3.2xlarge just because you want Arm but will end > up using just a quarter (maybe half if I'm generous) of the compute power. > It doesn't stack up for me. But YMMV. :) > > >> (I would also add that a big chunk of the data that is not read that >> frequently, so I might be ok with putting a specific set of tables on EBS) >> > > Interestingly, how do you plan to configure that? Unless I'm mistaken, C* > doesn't support tiered storage. Cheers! >
