Of course -- my point is simply that if you're looking for speed, SSD+KVM, especially in a shared tenant situation, is unlikely to perform the way you want to. If you're building a pure proof of concept that never stresses the system, it doesn't matter, but if you plan an MVP with any sort of scale, you'll want a plan to be on something more robust.
I'll also say that it's really important (imho) to be doing even your dev in a config where you have consistency conditions like eventual production -- so make sure you're writing to both nodes and can have cases where eventual consistency delays kick in, or it'll come back to bite you later -- I've seen this force people to redesign their whole data model when they don't plan for it initially. As I said, I haven't tested DO. I've tested very similar configurations at other providers and they were all terrible under load -- and certainly took away most of the benefits of SSD once you stressed writes a bit. XEN+SSD, on modern kernels, should work better, but I didn't test it (linode doesn't offer this, though, and they've had lots of other challenges of late). --DRS On Aug 3, 2013, at 11:40 PM, Ertio Lew <ertio...@gmail.com> wrote: > @David: > Like all other start-ups, we too cannot start with all dedicated servers for > Cassandra. So right now we have no better choice except for using a VPS :), > but we can definitely choose one from amongst a suitable set of VPS > configurations. As of now since we are starting out, could we initiate our > cluster with 2 nodes(RF=2), (KVM, 2GB ram, 2 cores, 30GB SDD) . Right now we > wont we having a very heavy load on Cassandra until a next few months till we > grow our user base. So, this choice is mainly based on the pricing vs > configuration as well as digital ocean's good reputation in the community. > > > On Sun, Aug 4, 2013 at 12:53 AM, David Schairer <dschai...@humbaba.net> wrote: > I've run several lab configurations on linodes; I wouldn't run cassandra on > any shared virtual platform for large-scale production, just because your IO > performance is going to be really hard to predict. Lots of people do, though > -- depends on your cassandra loads and how consistent you need to have > performance be, as well as how much of your working set will fit into memory. > Remember that linode significantly oversells their CPU as well. > > The release version of KVM, at least as of a few months ago, still doesn't > support TRIM on SSD; that, plus the fact that you don't know how others will > use SSDs or if their file systems will keep the SSDs healthy, means that SSD > performance on KVM is going to be highly unpredictable. I have not tested > digitalocean, but I did test several other KVM+SSD shared-tenant hosting > providers aggressively for cassandra a couple months ago; they all failed > badly. > > Your mileage will vary considerably based on what you need out of cassandra, > what your data patterns look like, and how you configure your system. That > said, I would use xen before KVM for high-performance IO. > > I have not run Cassandra in any volume on Amazon -- lots of folks have, and > may have recommendations (including SSD) there for where it falls on the > price/performance curve. > > --DRS > > On Aug 3, 2013, at 11:33 AM, Ertio Lew <ertio...@gmail.com> wrote: > > > I am building a cluster(initially starting with a 2-3 nodes cluster). I > > have came across two seemingly good options for hosting, Linode & Digital > > Ocean. VPS configuration for both listed below: > > > > > > Linode:- > > ------------------ > > XEN Virtualization > > 2 GB RAM > > 8 cores CPU (2x priority) (8 processor Xen instances) > > 96 GB Storage > > > > > > Digital Ocean:- > > ------------------------- > > KVM Virtualization > > 2GB Memory > > 2 Cores > > 40GB **SSD Disk*** > > Digitial Ocean's VPS is at half price of above listed Linode VPS, > > > > > > Could you clarify which of these two VPS would be better as Cassandra nodes > > ? > > > > > >
