Open Talk Series at Aditi illuminates new ideas

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Open Talk Series
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A series of illuminating talks and
interactions that open our minds to new availability.
ideas and concepts; that makes us look for
newer or better ways of doing what we
did; or point us to exciting things we have
never done before. A range of topics on Usually at 4.30PM Wednesdays.
Technology, Business, Fun and Life.

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New Champion

Sahil Sagar

Aditi Technologies | Partnering Innovation

Agenda

• We are not talking about crawler

• No discussion on PageRank… maybe?

4

The art of scale

10-50 users 100-500 users 500-10000
5

Scale ????

800,000 Machines

Largest Linux
Base

6

• What gives us this scale?

Good Code?

More servers?

Powerful
Servers?

7

• Lets see what gives Google the scale
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL The apps on top
GMAIL...
Python. Java. Python, Java, C++, of it.
C++ Sawzall, other

GWQ

Mapreduce
BigTable
BigTable The Secret Sauce
Chubby Lock

GFS / GFS II

INTERIOR NETWORK IPv6

RHEL 2.6.X PAE
Infrastructure
SERVER HARDWARE

RACK
DC
Exterior Network
8

Scale in Google
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL
GMAIL...
Python. Java. Python, Java, C++,
C++ Sawzall, other
1. The first touch
GWQ

Mapreduce
2. Size does matter
BigTable
BigTable
Chubby Lock

3. The Safe

GFS / GFS II
4. Operating System Implementation

RHEL 2.6.X PAE 5. Interior Network Architecture

SERVER HARDWARE

RACK
DC
Exterior Network

9

The first touch to the services

10

The first touch to the service
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
ENGINE
INDEX
CRAWL Client Browser Firewall
DMZ
GMAIL... 80/443 80/443
Perimeter Firewall
C++ Sawzall, other

GWQ

BigTable Mapreduce Squid GWS
BigTable Reverse Proxy Web Server Farm
Chubby Lock
NetScalar
http multiplexing Cell
Interior Network
GFS II etc
GFS / GFS II


RHEL 2.6.X PAE

SERVER HARDWARE

RACK
DC
Exterior Network
11

The touch is not always real
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL 80/443 80/443
GMAIL...
C++ Sawzall, other

GWQ
Squid
Reverse Proxy

BigTable Mapreduce
BigTable
Chubby Lock • Uses Squid Reverse Proxy

• Perimeter Cache hit rates 30-60% = Huge!
GFS / GFS II
• Dependent on search complexity/user preferences/traffic
type
RHEL 2.6.X PAE
• All Image Thumbnails caches, much Multimedia cached
SERVER HARDWARE

RACK
• Expensive common queries cached (common words like
DC
‘Obama‘) as they require significant back-end processing.
Exterior Network 12

Size does matter

13

Worldwide Data Centres
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL
GMAIL...
C++ Sawzall, other

GWQ

BigTable Mapreduce
BigTable
Chubby Lock

GFS / GFS II


RHEL 2.6.X PAE

SERVER HARDWARE

RACK Last estimated were 36 Data Centers, 300+ GFSII Clusters and upwards of
DC 800K machines.
Exterior Network
14

The Modular Data Centre
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL
GMAIL...
C++ Sawzall, other

GWQ

BigTable Mapreduce
BigTable
Chubby Lock

GFS / GFS II Standard Google Modular DC (Cell) holds 1160 Servers / 250KW Power
Consumption in 30 racks (40U).

RHEL 2.6.X PAE This is the “Atomic“ Data Centre Building Block of Google.

SERVER HARDWARE A Data Centre would consist of 100‘s of Modular Cells.
RACK
DC
Exterior Network
15

THE Safe

How is a server stored in the Data Centre?

16

Google Rack (GOOG rack)
Architecture
EVERYTHING custom!
GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL
GMAIL... • Optimized Motherboards
Python. Java.
C++
Python, Java, C++,
Sawzall, other • Have their own HW builds
GWQ • Build redundancy on top of
failure
BigTable Mapreduce
BigTable • Motherboard directly
Chubby Lock
mounted into Rack
• Servers have no casing -
GFS / GFS II
just bare boards
• Assist with heat dispersal
issues
RHEL 2.6.X PAE

SERVER HARDWARE

RACK
DC
Exterior Network 17

THE OPERATING SYSTEM

The Core Software on each of those servers

18

OPERATING SYSTEM
Architecture

GOOGLE APPS
GOOGLE APP
SEARCH
INDEX
-100% Redhat Linux Based since 1998 inception
ENGINE
CRAWL
GMAIL...
Python. Java. Python, Java, C++, - RHEL
C++ Sawzall, other
- 2.6.X Kernel
GWQ
- PAE
- Custom glibc.. rpc... ipvs...
Mapreduce
- Custom FS (GFS II)
BigTable
BigTable - Custom Kerberos
Chubby Lock - Custom NFS
- Custom CUPS
- Custom gPXE bootloader
- Custom EVERYTHING.....
GFS / GFS II

INTERIOR NETWORK IPv6 Kernel/Subsystem Modifications
tcmalloc – replaces glibc 2.3 malloc – much faster! works very well with threads...
RHEL 2.6.X PAE rpc – the rpc layer extensively modified to provide > perf increase < latency (52%/40%)

SERVER HARDWARE
Significantly modified Kernel and Subsystems – all IPv6 enabled

RACK
DC
Exterior Network
19

THE Secret Sauce

20

Section II – Googles Major Glue
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL
GMAIL...
C++ Sawzall, other

GWQ
1. Google File System Architecture – GFS II
BigTable Mapreduce
BigTable
Chubby Lock 2. Google Database - Bigtable

3. Google Computation - Mapreduce
GFS / GFS II


RHEL 2.6.X PAE

SERVER HARDWARE

RACK
DC
Exterior Network

21

GOOGLE FILE SYSTEM

Manages the underlying Data on behalf of the upper layers
and ultimately the applications

22

GFS versus NFS

Network File System (NFS) Google File System (GFS)

• Single machine makes part of  Single virtual file system spread over
its file system available to many machines
other machines  Optimized for sequential read
• Sequential or random access and local accesses
• PRO: Simplicity, generality,  PRO: High throughput, high
transparency capacity
• CON: Storage capacity and  "CON": Specialized for particular
throughput limited by single types of applications
server
23 University of Pennsylvania

FILE SYSTEM I – GFS II
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
INDEX
ENGINE
CRAWL
GMAIL...
C++ Sawzall, other

GWQ

BigTable Mapreduce
BigTable
Chubby Lock

GFS / GFS II


RHEL 2.6.X PAE
Elegant Master Failover

SERVER HARDWARE Chunk Size is now 1MB

RACK Only ever lost one 64MB chunk (in GFS I) during its entire production deployment so
DC assumed extremely reliable
Exterior Network 24

CAP Theorem
(Brewer's theorem)

• Consistency: All nodes see the same data at the same
time
• Availability: Node failures do not prevent survivors
from continuing to operate
• Partition tolerance: The system continues to operate
despite arbitrary message loss

25

GOOGLE DATABASE

Accesses the underlying Data on behalf of the upper layers
and ultimately the applications

26

Why not commercial DB?
• Scale is too large for most commercial databases
• Cost would be very high
– Building internally means system can be applied
across many projects for low incremental cost
• Low-level storage optimizations help
performance significantly
– Much harder to do when running on top of a database
layer
“Also fun and challenging to build large-scale
systems”
27

BigTable
• A distributed storage system for managing structured data.
• Scalable
– Thousands of servers
– Terabytes of in-memory data
– Petabyte of disk-based data
– Millions of reads/writes per second, efficient scans
• Self-managing
– Servers can be added/removed dynamically
– Servers adjust to load imbalance
• Used for many Google projects
– Web indexing, Personalized Search, Google Earth, Google Analytics,
Google Finance, …

28

BigTable

• Physically sorted on row-key – like a row-store
• Column families - like column-stores
• Variable (record-by-record) columns within a column family
• Column-values versioned; stored in reverse chronological order
• Designed to store hyperlink structure of web


GOOGLE MAPREDUCE

Computes the underlying Data on behalf of the applications

30

Mapreduce I
Architecture

GOOGLE APPS
SEARCH
GOOGLE APP
ENGINE
INDEX
CRAWL
Map Reduction can be seen as a way to exploit massive parallelism
GMAIL... by breaking a task down into constituent parts and executing on
C++ Sawzall, other multiple processors
GWQ
The Major Functions are MAP & REDUCE (with a number of intermediatary steps

BigTable Mapreduce MAP Break task down into parallel steps
BigTable
Chubby Lock REDUCE Combine results into final output

GFS / GFS II


RHEL 2.6.X PAE

SERVER HARDWARE
Shown is a 2-pipeline Map Reduction (There are 24 Map Reductions in the indexing pipeline)
RACK Mappers & Reducers usually run on separate processors (90% loss of reducers job still completed!)

DC
Exterior Network
31

Word-Count using MapReduce
Problem: determine the frequency of each word in a large
document collection


What runs on top of all this

33

PageRank: Intuition Shouldn't E's vote be
worth more than F's?

G A

H E B

How many levels I C
should we consider? F
J D

• Imagine a contest for The Web's Best Page
– Initially, each page has one vote
– Each page votes for all the pages it has a link to
– To ensure fairness, pages voting for more than one page must
split their vote equally between them
– Voting proceeds in rounds; in each round, each page has the
number of votes it received in the previous round
– In practice, it's a little more complicated - but not much!
34

Random Surfer Model
• PageRank has an intuitive basis in random walks
on graphs

• Imagine a random surfer, who starts on a random
page and, in each step,
– with probability d, clicks on a random link on the page
– with probability 1-d, jumps to a random page (bored?)

• The PageRank of a page can be interpreted as the
fraction of steps the surfer spends on the
corresponding page
35

BUILD YOUR OWN GOOGLE

The Basic Open Source Tools

36

The Google Stack (vs Yahoo‘ish/Open Source)

Open Source
(Yahoo’ish)
Architecture Architecture

GOOGLE APPS
SEARCH
APP ENGINE INDEX CLIENT APPLICATION
CRAWL
GMAIL...
Python, Java, Python, Java, C++, Pig Latin, Python, PHP, Java ....
C++, Sawzall, other anything

Task Queue GWQ Job Tracker

Googles Mapreduce Hadoop Framework
Hadoop
BigTable
Secret Sauce
BigTable
Chubby Lock
Mapreduce
Hbase (Bigtable equiv.)
Open Source
(Other Tools such as crawlers, indexers readily available)

GFS / GFS II HDFS (hadoop)

INTERIOR NETWORK IPv6 INTERIOR NETWORK IPv6

RHEL 2.6.X PAE CentOS 2.6.X PAE

SERVER HARDWARE SERVER HARDWARE

RACK RACK
DC DC
Exterior Network Exterior Network

Conceptual Overview
Google vs. Open Source 37

END

(Thankyou)

38

Pre Presentation
The Google Philosophy (according to ed)

• Jedis build their own lightsabres (the MS Eat your own Dog Food)
• Parallelize Everything
• Distribute Everything (to atomic level if possible)
• Compress Everything (CPU cheaper than bandwidth)
• Secure Everything (you can never be too paranoid)
• Cache (almost) Everything
• Redundantize Everything (in triplicate usually)
• Latency is VERY evil

39

Special Thanks to ….

The Anatomy of the Google Architecture
“The unofficial Version“

V1.0 November 2009

• Ed Austin
• {ed, edik} @i-dot.com


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Open Talk Series at Aditi illuminates new ideas

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