Showing results for 
Search instead for 
Did you mean: 

AWS c3 instances

When AWS announced c3 instances, AWS made a lot of noise about them.  What do people think about the c3 instances?  Are m3.large and m3.xlarge better than c3s?


the m3 and c3 family are

the m3 and c3 family are quite similar, save for these key differences:

  • higher vcpu:mem ratio on c3
  • higher clock rate per vcpu on c3
  • ability to scale beyond 8 vcpu on c3
  • option of "enhanced networking" on c3/r3/i3 ... will explain that later

For example, here are some cost-comparable instances:

c3.large273.752 x 16 SSD$0.105 per Hour
m3.large26.57.51 x 32 SSD$0.140 per Hour
c3.xlarge4147.52 x 40 SSD$0.210 per Hour
m3.xlarge413152 x 40 SSD$0.280 per Hour
c3.2xlarge828152 x 80 SSD$0.420 per Hour
m3.2xlarge826302 x 80 SSD$0.560 per Hour


If core count is more important than memory (routing applications often don't require a lot of ram), then c3 is a clear win. In addition, the c3 types support "enhanced networking" in HVM mode, which allows the ixgbevf driver (if properly installed), to virtualize the NIC, and provide multiple hardware interruptes into the VM. It's perfect for high network I/O, like routing applications need, and won't over-saturate a single vcpu with too many interrupts. 

I am testing the CSR1000V today. I hope to see Cisco has a compatible ixgbevf driver in their AMI, but I'm not holding my breath.

For most of my applications, I find c3.* to be the ideal instance type for many workloads. I also mix in some r3.* for memory-pigs like redis. 

CreatePlease to create content
Content for Community-Ad
August's Community Spotlight Awards