You have a video transcoding application running on Amazon EC2. Each instance polls a queue to find out
which video should be transcoded, and then runs a transcoding process. If this process is interrupted, the
video will be transcoded by another instance based on the queuing system. You have a large backlog of videos
which need to be transcoded and would like to reduce this backlog by adding more instances. You will need
these instances only until the backlog is reduced. Which type of Amazon EC2 instances should you use to
reduce the backlog in the most cost efficient way?
A.
Reserved instances
B.
Spot instances
C.
Dedicated instances
D.
On-demand instances
Explanation:
http://aws.amazon.com/ec2/purchasing-options/spot-instances/
B.
Key word is “most cost efficient way?”
B
I agree with the answer. B
B
D, this is the most suitable for the case.
B : the spot instance cannot be grantee for the period of the backlog, so be is wrong.
Yes, i think D, too.
B
B
B
https://aws.amazon.com/ec2/faqs/
Spot instances provide the ability for customers to purchase compute capacity with no upfront commitment, at hourly rates usually lower than the On-Demand rate. Spot instances allow you to specify the maximum hourly price that you are willing to pay to run a particular instance type. Amazon EC2 sets a Spot Price for each instance type in each availability zone, which is the hourly price all customers will pay to run a Spot instance for that given period. The Spot Price fluctuates based on supply and demand for instances, but customers will never pay more than the maximum price they have specified. If the Spot Price moves higher than a customer’s maximum price, the customer’s instance will be shut down by Amazon EC2. Other than those differences, Spot instances perform exactly the same as On-Demand or Reserved Instances. See here for more details on Spot instances.
The correct answer is “D” (On Demand Instance). Spot instances are more applicable as “auctions” as a discounted rate and you need to apply for that. Whenever you have any “time” depended activity ( more or less during a specific period of time), the most common approach is to go for “On Demand” option.
Question says ‘most cost efficient way’ and ‘if this process is interrupted, the
video will be transcoded by another instance based on the queuing system.’ .That definitely makes it ‘B’.
B.
If this process is interrupted, the video will be transcoded by another instance based on the queuing system. Obviously if the the spot instance is killed, no worries there.
Despite spot instances being the cheapest, you need to take into consideration that the scenario calls to reduce urgently the backlog of videos. So you cant allow yourselves using spot instances when it can be shut down anytime if your under bid.
I would go for On demand instances
B
B.
You need to reduce backlog without spending much on it.
with Spot instances you can significantly reduce the cost of running your applications, grow your application’s compute capacity and throughput for the same budget, and enable new types of cloud computing applications.
Agree with B..
Objective is reduce the backlog with no strict timeline and in most cost efficient way.
Another point is “If this process is interrupted, the video will be transcoded by another instance based on the queuing system.”
On-Demand sounds good if the solution is not sensetive to cost and if the transcoding doesnot tolerate interruption.
In this case, there is a clear benefit of picking Spot instances over On-Demand.
Who guarantees you that you will ever hit the spot price and for the time long enough to reduce the log efficiently?
On Demand instances : you pay the time you use them to reduce the log and that’s it. No commitment, no additional cost. That is what I call cost efficient!
The answer is D.
“You have a large backlog of videos which
need to be transcoded …”
So you have already a problem, you have a large backlog and you can not wait for the spot instance price to hit your spot instance price. You need to act now.
Again, the answer is : ON-DEMAND instance