Re:AWS X1 instances – 1.9 TB of memory
by sun_n_surf on Thursday May 19, 2016 @12:14PM
(#11731280)
Not sure I quite understand your math here. The largest R3 instance is the r3.8xlarge with 244 GB of memory. 4 times of that would only get you to 1 TB. Also, this: "DRAM is valuable precisely because of its speed", is wrong (https://en.wikipedia.org/wiki/Dynamic_random-access_memory).
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1. 4 of those R3 instances cost less than the X1 but offer nearly double the bandwidth. The X1 is cheaper per GB, but much more expensive per GB/s.
2. If DRAM was not faster than NVRAM/SSD, nobody would use it. "Speed" involves both bandwidth and latency. Latency is probably similar or higher for the X1 instances, but I haven't seen numbers. We can make better estimates about realizable bandwidth based on the system stats.