> We do simple 'rack' awareness based on the AZ returned by the metadata server
Just want to add a datapoint that I do this too -- for simulating racks when running test clusters up on EC2 (it corresponds to physical properties and makes it easy to group instances for nuking a whole "rack") -- and have encountered no major problems. I can also echo the comments of others that cross-AZ deployments can see significant delay and variance on the network. On Mon, May 6, 2013 at 3:26 PM, Steph Gosling <[email protected]> wrote: > Hi, > > On Mon, 6 May 2013 14:47:49 -0400 > Otis Gospodnetic <[email protected]> wrote: > > > Yup. I'm suddenly turned off by that penny per GB! :) > > Ignoring the dollars, it sounds like one would just have to be OK with > > increased latencies, but technically nothing would break. Doodling > > our architecture on paper here, I think we may as well just have > > complete, independent setups in multiple Regions then - I suspect > > those pennies add up faster than one would think. > > > > Otis > > I run a couple of small HBase clusters (low double-digit nodes each), > and both span AZs in their respective regions (we're not doing any > inter-region stuff yet, nor do I expect to,TBH). What AWS don't tell > you is that not all instance types are available in all AZs, > particularly for the newer or more esoteric instances. > > We care about this data so any performace hit (not that we've > particularly noticed one) because of cross AZ traffic is acceptable. We > do simple 'rack' awareness based on the AZ returned by the metadata > server, you could probably fine-tune that based on subnet if your > cluster got big but we've not had the need to. > > With regards to performance specifically, I've not looked explicitly > but I'd expect that you'll see far more variance based on things like > instance size, your neighbours on the same host and their behaviour. > > Finally, I'm also surprised about the inter-AZ data charges, that seems > to be a very wide-spread misconception, and yeah I'd imagine the > pennies do add up... > > Cheers, > > Steph > -- > Steph Gosling <[email protected]> > -- Best regards, - Andy Problems worthy of attack prove their worth by hitting back. - Piet Hein (via Tom White)
