The m6g.2xlarge pairs 8 vCPU with 32 GiB of RAM, the 4.00 GiB-per-vCPU ratio that marks a general-purpose instance. In the name, "m" is the general-purpose line, "6" is the generation, "g" marks AWS Graviton (ARM) processors and "2xlarge" is the size within the m6g family. It runs on AWS Graviton2 Processor at 2.5 GHz, and AWS introduced it in May 2020. AWS has since shipped m7g, m8g and m9g; m7g.2xlarge is the direct replacement at this size, scoring 199,154 CoreMark/s against this instance's 154,689 — roughly 29% more throughput for the same vCPU count. gp.vs2.xlarge on Rackspace Spot lines up one-for-one: 8 vCPU and 32 GiB, about 90% below the US East (N. Virginia) on-demand rate.
Match qualityx86 substitution
m6g.2xlarge is Graviton (arm64). Rackspace Spot does not have arm64 servers, so gp.vs2.xlarge is an x86_64 substitute with similar specs.
You will need x86 builds of your container images. Most software rebuilds without changes, but anything with compiled native code needs a real rebuild rather than a retag. Speed per core also differs between the two chips, so it is worth testing before deciding how many nodes to run.
