Amazon just announced a reserved instances plan for EC2. This new option significantly reduces costs for Linux/UNIX users. This option is not available for Windows users as of this time. The way it appears to work is this:
- User buys block of hours that is good for a 1 or 3 year term.
- User consumes hours and has this usage debited from the prepaid block of time.
- If the user fails to consume their hours within the 1 or 3 year term, the money is gone.
The 1 year blocks sell 10833 hours. The 3 year blocks represent 16667 hours. For comparison, a week has 168 hours, a year has 8760 or 8784 hours (leap year dependent). Here’s a cost comparison of the offerings:
|
1 yr Block of hours |
Pay as you go |
3 yr Block of hours |
Pay as you go |
|
|
Standard/Small |
$325.00 |
$1,083.33 |
$500.00 |
$1,666.67 |
|
Standard/Medium |
$1,300.00 |
$4,333.33 |
$2,000.00 |
$13,333.34 |
|
Standard/Large |
$2,600.00 |
$8,666.66 |
$4,000.00 |
$13,333.34 |
|
High CPU/Medium |
$650.00 |
$3,250.00 |
$1,000.00 |
$5,000.00 |
|
High CPU/Large |
$2,600.00 |
$13,000.00 |
$4,000.00 |
$20,000.00 |
A couple of things jump out at me. First, I wonder if anyone would ever use the Standard/Large instance when the High CPU/Large was available for the same price. The only use case I see is where someone has a Standard/Large humming along perfectly and they don’t want to incur the costs for testing the switch. It seems like it will be cost effective to run a server all year round at these new prices– depending of course on your storage needs.
With these reserved instances, there are a number of restrictions. Keep in mind that Amazon is able to reduce the prices because you are agreeing to lock yourself into a usage mode. In order for you to win, they need to win too! What are the restrictions? From the FAQ, I see these:
- You can purchase 1 to 20 instances through website. Instances 21+ require special permission (though it doesn’t look onerous).
- Reserved instances live in one and only one availability zone. You are locked into that one for the contract duration. This shouldn’t be a huge restriction since, even when you purchase ahead of time, you come out ahead after consuming 20% of your hours in a high CPU contract and after 30% of your hours in the standard plans
- Once you purchase an instance type, you can’t convert things to a different instance type later. You stick with what you purchased. Again, risk is low since if you made a mistake, you can throw away 69% of your hours and still come out ahead of the pay as you go route.
- As mentioned above, if you don’t use it, you lose it. Unconsumed hours disappear after the 1 or 3 year term.
This looks like a good deal. I can’t wait until the comparable Windows plan is rolled out!
Karmic Code Monkey 