Amazon EC2 Costs - A reality check

Ever since Amazon introduced its EC2 virtual computing environment, the disruptive pricing has been crucial to disrupting the market. However, it is quite easy for vendors / System Integrators to think moving to "cloud" would dramatically lower the costs, while in some cases, the costs may go up!

Here's what you see you on the EC2 website when you want to find the costs:

Looking at the pricing in the image above, you'd think the cost aren't going to be that high. Most of the people I have come across, only remember the soundbyte of 34 cents/hour.

However, simple math dictates the yearly costs could be fairly substantial as the table below depicts:

OS	EC2 Instace	Demand Type	Cost / Hr	Hours	Length	Total
Windows	HCPU Extra Large	OnDemand	$1.16	8,736	Year	$10,133.76
Windows	Extra Large	OnDemand	$0.96	8,736	Year	$8,386.56
Linux/UNIX	Extra Large	OnDemand	$0.68	8,736	Year	$5,940.48
Linux/UNIX	HCPU Extra Large	OnDemand	$0.68	8,736	Year	$5,940.48
Linux/UNIX	Large	OnDemand	$0.68	8,736	Year	$5,940.48
Windows	HCPU Extra Large	Reserved	$0.50	8,736	Year	$4,368.00
Windows	Large	OnDemand	$0.48	8,736	Year	$4,193.28
Windows	HCPU Medium	OnDemand	$0.29	8,736	Year	$2,533.44
Linux/UNIX	Extra Large	Reserved	$0.24	8,736	Year	$2,096.64
Linux/UNIX	HCPU Extra Large	Reserved	$0.24	8,736	Year	$2,096.64
Linux/UNIX	HCPU Medium	OnDemand	$0.17	8,736	Year	$1,485.12
Linux/UNIX	Large	Reserved	$0.12	8,736	Year	$1,048.32
Windows	Small	OnDemand	$0.12	8,736	Year	$1,048.32

The table above lists the costs of various "instances" of the compute units offered by Amazon, the hourly costs for them, and the corresponding yearly costs. These "instances" can have either Linux/Unix OS or Windows (priced differently), and you can even choose to "reserve" an instance for your use, which may even save some money. 

Clearly, computing cost on EC2 isn't as cheap as it seems initially. For example, something called an "Extra Large" instance will cost upwards of $8,000 per year, while "HCPU Extra Large" will cost over $10,000. Further, it isn't clear what this "instance" is, and what is included in an instance. So a little more digging is necessary to determine what is meant by, or included in, various instances. Here's a handy table describing the instances:



Instance	Memory (MB)	Virtual  Core	ECU	ECU per Core	Storage (GB)	I/O	Platform
Micro Instance	633	1	2	-			32/64 bit
Small Instance – default	1740.8	1	1	1	160	Moderate	32 bit
Large Instance	7680	2	4	2	850	High	64 bit
Extra Large Instance	15360	4	8	2	1690		64 bit
High-Memory Extra Large Instance	17510.4	2	6.5	3.25	420	Moderate	64 bit
High-Memory Double Extra Large Instance	35020.8	4	13	3.25	850	High
High-Memory Quadruple Extra Large Instance	70041.6	8	26	3.25	1690		64 bit
High-CPU Extra Large Instance	7168	8	20	2.5	1690	High	64 bit
Cluster Compute Quadruple Extra Large Instance*	18432	8	33.5	4.1875	1690	Very Large	64 bit
Cluster GPU Quadruple Extra Large Instance **	18432	8	33.5	4.1875	1690	Very Large	64 bit

The above table lists the various instances offered by Amazon, the memory included (in MB) for each instance type, the virtual processors for each instance, storage (in GB) and whether the instance is available in 32 or 64 bit support. Also provided is a breakdown of Elastic Compute Unit (or ECU), per virtual processor core. The idea here is to provide all permutations of the most common computing needs that the large majority of consumers would have, and offer computing in those flavours. 

The GPU instance is a recent addition, providing graphic intensive core, therefore obviating the need for small businesses to buy specialised servers to perform graphic intensive tasks (such as computer aided animation or design, etc). However, you'll need to dig further to determine exact what is a virtual processor - and this is where wikipedia comes to rescue. An EC2 Compute Unit (in other words, the virtual processor in each of these instances offered by Amazon) is roughly equivalent of a 1.0 to 1.2 Ghz 2007 Xeon or Opteron processor. It has a CPU passmark of approximately 400. However, some websites report a lower passmark.

Armed with all that information, if you then decide to request Amazon for provisioning a set of instances to serve up your website, storefront, etc., beware! There are a lot more elements that make your final (monthly) bill. Here's a quick peek at the most common customer examples available at Amazon EC2 website:

Sample Scenario	Instances	EC2 Total	S3 Total	VPC total	DB Total	Cloud Front Total	Discount	Data	Total
Marketing Web Site	2 Large	1054.08	605.72	0	0	197.8	-4.5	74.8	1927.9
Web Application	5 Large 2Xlarge	4256.41	2771.12	471.5	434.9	0	-24.52	2274.19	10183.6
Media Application	None	0	42.02	100	0	853.33	-1.85	1.15	994.65
HPC Cluster	None	0	780.76	5510.4	0	0	-4.45	1117.7	7404.41
Disaster Recovery & Backup	None	1610.4	364.07	0	0	0	-4.47	318.05	2288.05
European Web App	None	2191.58	98.66	21.79	21.79	0	-26.32	463.95	2771.45

If you think the table above is scary, then..well yeah, it is. It contains a flavour of the variables that Amazon uses to calculate the price per month that it will charge you, and clearly there's more to the cost than merely the compute currency. Some of the key elements that go into it are:

• Compute Unit (as we discussed)
• Usage (in hours)
• Location of usage (Amazon offers US East Coast, US West Coast, Europe and Asia Pacific
• Additional Amazon services used, such as:
  • Elastic IP address remapping
  •  Amazon Elastic Block Store (EBS)
  • Elastic Load Balancing
  • Amazon CloudWatch
  • Amazon Web Services
  • Amazon S3
  • Virtual Private Cloud
  • etc...

Clearly, there is a lot more to Amazon's pricing than the promise of 10 cents/hour. Perhaps these are the variables that every Data Center administrator has to work with, when planning to install new equipment. However, to some extent, this disruptive pricing and offering requires a fairly steep curve for rest of the market. I suppose the initial adopters would be technology enthusiasts AND more importantly, competitors, which would do nothing but add fuel to the fire of Amazon's advertising for this offering! 

Next time - more details on the EC2 pricing!

–Elast