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Decision Support for Amazon EC2 Spot Instances
Fei Dong 2011-‐11-‐28
11/27/11 1
A Glimpse of Amazon EC2
EC2 Node Type
CPU (#EC2 units)
Memory I/O Performance
Per-‐hour Cost
m1.small 1 1.7 GB moderate $0.085
m1.large 4 7.5 GB high $0.34
m1.xlarge 8 15 GB high $0.68
c1.medium 5 1.7 GB moderate $0.17
c1.xlarge 20 7 GB high $0.68
cc1.4xlarge 33.5 23 GB very high $1.60
• Reserved Instance, On-‐demand Instance, and SI • Different scenarios: Cluster × Workload
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MulU-‐objecUve Cluster Provisioning
0 200 400 600 800
1,000 1,200
m1.small m1.large m1.xlarge c1.medium c1.xlarge
Run
ning
Tim
e (m
in)
Actual
0.00 2.00 4.00 6.00 8.00
10.00
m1.small m1.large m1.xlarge c1.medium c1.xlarge
Cos
t ($)
EC2 Instance Type for Target Cluster
Actual
3
Spot Instance
• Spot instances enable you to bid for unused Amazon EC2 capacity. Instances are charged the Spot Price which is set by Amazon EC2 and fluctuates periodically depending on the supply of and demand for Spot Instance capacity.
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Challenges & AssumpUons
• Challenges: – Minimize monetary costs for a user while meeUng Service constrains.
– Know nothing about Amazon pricing strategy and other bid strategy.
• AssumpUons: – Bid price is fixed. – Instance Type is fixed (no mix strategy) – Not consider the overhead to recover spot instances.
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Pricing PredicUon Model
• Linear Regression • Normal DistribuUon • ExponenUal DistribuUon
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p (1− p )i −1i =1
n
∑ H (i )
Predict Price Algorithm
1. Collect the prices over a period of Ume, in order to esUmate mean and variance.
2. Use the exponenUal approximaUon fidng, calculate x given the CDF(X<x) = Prob.
3. Compare other models and pick a maximum value as a bid price.
4. If the bid price is smaller than the spot price, thus increase the bid by 33% for the next interval.
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Price PredicUon
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0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Price ($)
Time (Hours)
eu linux.m1.small spot price on 11/18/2011
Actual
Predict Adjust
Predict
Var(Predict Adj) = 0.000769 Var(Predict) = 0.001786
Bid Strategy
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copt = argmaxc∈S
F(d,b,e, t,n)Utility = F(d,b,e, t,n) Deadline d, budget b,
Estimated Time e, Cluster Type t,
Number n
Min Time Mode: Can the job be execute as soon as possible under specified budget and deadline constrains?
Min Money Mode: What is the bid price and instance type that minimize the total monetary cost?
ExhausUve Search
Experimental EvaluaUon
• Choose 5 Spot Instance Types – M1.small, m1.large, m1.xlarge, c1.medium, c1.xlarge
• Run 5 Instances compared with on demand instances.
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Experimental EvaluaUon (Ctd.)
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0
2
4
6
8
10
12
14
m1.small m1.large m1.xlarge c1.medium c1.xlarge
Cost ($
)
EC2 Instance Type
on-‐demand
SI budget intensive
SI Ume intensive
0
200
400
600
800
1000
1200
1400
1600
m1.small m1.large m1.xlarge c1.medium c1.xlarge
Runn
ing Time (M
in)
EC2 Instance Type
on-‐demand
SI budget intensive
SI Ume intensive
Case Analysis
11/27/11 12 M1.small spot instance, bid strategy
M1.small Linux on 11/18/2011
Conclusions & Future Work
• Conclusions – More cost-efficient than fixed-size instance choice – Spot Instances not always provide inexpensive resources
for transient workloads
• Future works – Consider to mix other instance types (e.g. spot
instances & reserved instances) – Disaster Recovery, checking point.
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Reference • hjp://aws.amazon.com/ec2/instance-‐types • H. Herodotou, F. Dong, and S. Babu. No One (Cluster) Size Fits All:
AutomaUc Cluster Sizing for Data-‐intensive AnalyUcs. (Slides)In Proc. of the ACM Symposium on Cloud CompuUng 2011 (SOCC '11), October 2011.
• D. Ardagna, B. Panicucci and M.Passacantando. A Game TheoreUc FormulaUon of the Service Provisioning Problem in Cloud Systems. WWW2011 Proceedings, 2011
• N. Jain, I. Menache, and O. Shamir. On-‐demand or Spot? Learning-‐based Resource AllocaUon for Delay-‐Tolerant Batch CompuUng.
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Thank youJ
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