This document summarizes the results of benchmark tests performed on Amazon RDS instances with varying configurations. The tests measured MySQL database performance using mysqlslap under different levels of concurrency and across small, large, xlarge, 2xlarge, and 4xlarge EC2 instance types with a standardized 100GB EBS volume. The results show that increasing the instance type size improves database performance more significantly than increasing the EBS volume size. Larger instances are less impacted by contention on shared hardware resources.

1. RDS Write i/o BenchmarK
AWS RDS instance type comparison
Roberto Gaiser
@rgaiser

2. RDS
• MySQL / Oracle / SQL Server
• Running on EC2 managed by AWS, patches, replication
and backup
• EBS (Elastic Block Store) for storage
• EBS = network block device
• “Black Box” = no “shell” access
• 1 EC2 Compute Unit =1.0-1.2 GHz 2007 Opteron or
2007 Xeon processor

3. RDS
• MySQL / Oracle / SQL Server
• Running on EC2 managed by AWS, patches, replication
and backup
• EBS (Elastic Block Store) for storage
• EBS = network block device
• “Black Box” = no “shell” access
• 1 EC2 Compute Unit =1.0-1.2 GHz 2007 Opteron or
2007 Xeon processor

4. Instance Comparison
EC2 Compute
Memory GB Cores Price/Hour *
Unit
Small 1.7 1 1 $0.105
Large 7.5 4 2 $0.415
XLarge 15.0 8 4 $0.830
2XLarge 34.0 13 4 $1.170
4XLarge 68.0 26 8 $2.340
* Price for us-east-1

5. Instance Comparison
EC2 Compute
Memory Price/Hour
Unit
Small 1 1.0 1.0
Large 4 4.4 4.0
XLarge 8 8.8 7.9
2XLarge 13 20.0 11.1
4XLarge 26 40.0 22.3

6. Instance Comparison
Instance Types Comparison
70
60
50
Memory GB
40
31
21
11
1
1 5 8 12 15 19 22 26
EC2 Compute Unit
Small Large XLarge 2XLarge 4XLarge

7. Test Setup
• MySQL
• Two data sets:
• Increase instance size
• Increase EBS size
• Different days and periods
• 5.5.20
• max_connections parameter

8. Test Setup
• Ubuntu 12.04 LTS AMI Ubuntu 12.04 LTS
AMI ami-a29943cb
• mysqlslap from Ubuntu MySQL repository
• EC2 High-CPU Medium c1.medium
• Disk I/O bound:
✓ insert and commit

9. mysqlslap
mysqlslap -uXXXX -pXXXXX
--concurrency=1,5,10,20,30,50,100,200,400 --
engine=innodb
--auto-generate-sql --auto-generate-sql-load-type=write
--auto-generate-sql-add-autoincrement --auto-generate-sql-
secondary-indexes=1
--commit=1 --number-of-queries=40000 --iterations=5
-h XXXXX.rds.amazonaws.com --csv=XXXXXX.csv

10. mysqlslap
mysqlslap -uXXXX -pXXXXX
--concurrency=1,5,10,20,30,50,100,200,400 --
engine=innodb
--auto-generate-sql --auto-generate-sql-load-type=write
--auto-generate-sql-add-autoincrement --auto-generate-sql-
secondary-indexes=1
--commit=1 --number-of-queries=40000 --iterations=5
-h XXXXX.rds.amazonaws.com --csv=XXXXXX.csv

11. EBS x Instance Type
• Chart using the 100GB EBS volume data
• Same EBS on all tests
• EBS are not created equal
• No replication
• us-east-1

12. Change Instance Type
RDS Instance MySQL EBS Volume
EBS Volume
RDS Instance MySQL

13. 100GB EBS

14. 100GB EBS

15. 100GB EBS

16. 100GB EBS

17. 100GB EBS

18. Guerrilla Capacity
planning
N
C(N ) =
1 + ↵(N 1) + N (N 1)
• Universal Scalability Law (USL)
• http://www.perfdynamics.com/Manifesto/USLscalability.html
• Guerrilla Mantra 1.16: Data are not divine. Data comes from
the Devil, only models come from God.
• Guerrilla Mantra 2.25: All measurements are wrong by
definition.
• R using nls() http://www.perfdynamics.com/Classes/Materials/USLcalc.r

19. 100GB EBS

20. 100GB EBS

21. 100GB EBS

22. 100GB EBS

23. 100GB EBS

24. 100GB EBS

25. N Max X Max
small 59.48 1660.29
large 88.46 3859.50
xlarge 134.40 6068.01
2xlarge 204.00 7228.87
4xlarge 217.55 8172.99

26. N Max X Max N X
small 59.48 1660.29 1.00 1.00
large 88.46 3859.50 1.49 2.32
xlarge 134.40 6068.01 2.26 3.65
2xlarge 204.00 7228.87 3.43 4.35
4xlarge 217.55 8172.99 3.66 4.92

27. X Max

28. N Max

29. α contention β coherency
small 0.0590 2.66E-04
large 0.0586 1.20E-04
xlarge 0.0466 5.30E-05
2xlarge 0.0403 2.3E-05
4xlarge 0.0360 2.0E-05

30. α contention β coherency α β
small 0.0590 2.66E-04 1.00 1.00
large 0.0586 1.20E-04 0.99 0.45
xlarge 0.0466 5.30E-05 0.79 0.20
2xlarge 0.0403 2.30E-05 0.68 0.09
4xlarge 0.0360 2.00E-05 0.61 0.08

31. Instance type x EBS
• Same instance and EBS endpoints for each
test
• EBS are not created equal
• No replication
• us-east-1

32. Change EBS Size
RDS Instance MySQL EBS Volume
RDS Instance MySQL
EBS Volume

33. Large Instance

34. XLarge Instance

35. 2XLarge Instance

36. 4XLarge Instance

37. Small Instance

38. EC2 Price/
Compute Memory α N Max X Max
Unit
Hour
small 1.0 1.0 1.00 1.00 1.00 1.0
large 4.0 4.4 0.99 1.49 2.32 4.0
xlarge 8.0 8.8 0.79 2.26 3.65 7.9
2xlarge 13.0 20.0 0.68 3.43 4.35 11.1
4xlarge 26.0 40.0 0.61 3.66 4.92 22.3

39. Conclusion
• EBS size has no effect on I/O performance
• Small instances are more affected by other
instances on the same server
• Larger instances have a greater share of the
physical resources, more network
throughput translates to more EBS I/O

40. Conclusion
• More instances on the same server, more
concurrency. α increases
• Small decrease in α increases the
throughput by a large amount
• EBS are not created equal