CIT 668: System Architecture. Scalability

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1 CIT 668: System Architecture Scalability

2 1. Scales 2. Types of Growth 3. Vertical Scaling 4. Horizontal Scaling 5. n-tier Architectures 6. Example: Wikipedia 7. Capacity Planning Topics

3 What is Scalability scalability(n): the ability of something, especially a computer system, to adapt to increased demands - dictionary.com

4 Scalability Scalability is not about how fast your system is. Scalability focuses on the question if you double the number of servers, is your system twice as fast? Speed matters, since if your servers are twice as fast, you only need to buy half as many, but it s not the same as scalability.

5 Scales

6 Physical Scales m 10 6 m m

Physical Scales and Technology 10-15 10-10 10-8 1m

7 Physical Scales and Technology m 10 3 m 10 6 m m Intel m IBM Khalifa NASA

8 Orders of Magnitude from to m Atomic to Cellular Human Scales Astronomical Scales

10 Types of Growth

11 Linear, Cubic, and Exponential Growth

12 Moore s Law is Exponential

13 Internet Growth

14 Data Center Energy Growth

15 Supercomputer Performance

16 Horizontal and Vertical Scaling

17 Vertical Scaling

18 Plenty of Fish 1.2 billion page views per month, 500,000 average unique logins per day 30+ million hits per day, per second 45 million visitors per month top 30 site in the US, top 10 in Canada, top 30 in the UK 2 load balanced Windows Server 2003 x64 web servers with 2 Quad Core 2.66Ghz CPUs, 8 GB RAM, 2 hard drives 3 database servers. No data on their configuration Approaching 64,000 simultaneous connections and 2 million page views per hour Internet connection is a 1 Gbps line, 200 Mbps is used 1 TB per day serving 171 million images through Akamai 6 TB storage array to handle millions of full sized images uploaded every month to the site

19 Plenty of Fish Scaling We upgraded from a machine with 64 GB of ram and 8 CPU s to a HP ProLiant DL785 with 512 GB of ram and 32 CPU s and moved from SQLserver 2005 to 2008 and windows Markus, s-themes-date-night/ Estimated cost ~ $100,000

20 Horizontal Scaling

21 Load Balancing Internet Load Balancer Server 1 Server 2 Server N

22 Googol = Sun Ultra MHz processors First Rack 8 CPUs 200 GB Large Container Data Centers > 10 6 servers

23 Horizontal vs. Vertical Scaling Example Total budget is $100,000 Vertical: PoF HP ProLiant DL785 32CPU,512GB Horizontal: 83 1U servers for $1150 each Lenovo ThinkServer RS110 barebones $600 8 GB RAM $100 2 x ebay drive brackets $50 2 x 500 GB SATA hard drives, mirrored $100 Intel Xeon X GHz quad-core CPU $300 Comparison: Scaling Up Scaling Out CPUs RAM 512 GB 664 GB Disk 4 TB 40.5 TB

24 n-tier Architectures

25 Horizontal Problem: DB Synchronization Internet Load Balancer Web Server 1 DB Server 1 Web Server N DB Server N Server 1 Server 2 Server N

26 Solution: Use a Single Database Load Balancer Web Servers DB Server

27 n-tier Architecture Presentation Tier User interface: Client UI + web server Application Tier Business logic Web server dedicated to dynamic content Data Tier Databases (dynamic data) Filesystems (static data)

28 n-tier Architecture Separating system into tiers enables Each tier to scale horizontally, thus allowing Greater horizontal scalability than 1-tier architectures. n-tier advantages Tier-specific security policies can be tighter. Can separate management of tiers. n-tier disadvantages Complexity of design and management Communication overhead between tiers

29 Scaling the Data Layer Load Balancer Web Servers DB Master (read/write) writes reads Load Balancer DB Replicas (read-only)

30 Scaling Example: Wikipedia

31 Wikipedia Architecture 2004

32 Wikipedia Architecture 2005

33 Wikipedia Architecture 2006

34 Wikipedia Architecture 2008

35 Wikipedia Architecture 2010

36 Capacity Planning

37 Wikipedia Traffic Metrics Peak Traffic

38 Effect

39 Scaling Projections

40 Key Points 1. Scalability is not about how fast your system is; it s about how performance grows with increasing resources. 2. Vertical scaling ( scaling up ) means getting a faster server with more storage. 1. Vertical hits a ceiling when you get the biggest machine available (or affordable.) 3. Horizontal scaling ( scaling out ) means getting a larger number of servers. 1. Horizontal hits Amdahl s law ceiling much later than vertical hits hardware ceiling.

41 References 1. AWS, Getting Started with AWS CloudFormation, ation/latest/userguide/gettingstarted.html. 2. Theo Schlossnagle, Scalable Internet Architectures, Sams Publishing, 2007.

CISC 7610 Lecture 5 Distributed multimedia databases. Topics: Scaling up vs out Replication Partitioning CAP Theorem NoSQL NewSQL

CISC 7610 Lecture 5 Distributed multimedia databases Topics: Scaling up vs out Replication Partitioning CAP Theorem NoSQL NewSQL Motivation YouTube receives 400 hours of video per minute That is 200M hours