!"" Million Active Users

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## property on the Internet (time on site)

)""s of billions of monthly page views

>$ trillion feed actions processed per day

)""s of millions of cache queries per second

Over # trillion objects cached

Over !"" million active users, half log in every day

)"" billion photo files stored

Over #" billion minutes spent every Day

Over # billion pieces of content uploaded every week

Move FastServer ScalingReliability

!"" Million Active Users

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Over ) million active users per engineer

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Facebook Google* Amazon* Microsoft*

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* Conservative estimates based on publicly available data

Few external deadlines... but

The site can’t go down

Frequent small changesNever a delay waiting for a pushEasier to isolate bugs

Major changes dark launched

Traditional websites

Bob

Bob’s data

Traditional websites

Bob

Bob’s data

Julie

Julie’s data

Dan

Dan’s data

Beth

Beth’s data

Sue

Sue’s data

Erin

Erin’s data

Facebook the data is interconnectedBob ErinBeth

Servers

Scale Horizontally

Database

Memcache

Web Server

Database

Memcache

Web Server

Database

Memcache

Web Server

Database

Memcache

Web Server

Network Incast

Memcache Memcache Memcache Memcache

Switch

PHP Client

Network Incast

Many SmallGet Requests

Memcache Memcache Memcache Memcache

Switch

PHP Client

Memcache Memcache Memcache Memcache

Switch

PHP Client

Many bigdata packets

Network Incast

Memcache Memcache Memcache Memcache

Switch

PHP Client

Network Incast

Memcache Memcache Memcache Memcache

Switch

PHP Client

Network Incast

Memcache Memcache Memcache Memcache

Switch

PHP Client

Network Incast

Reliability

Single Points of Failure

Single Points of FailureSoftware can be a SPOF

Don’t make small problems big

Don’t make small problems bigDon’t push problems upstream

Don’t make small problems bigDon’t push problems upstreamBe wary of “smart” failover

Don’t make small problems bigDon’t push problems upstreamBe wary of “smart” failoverShed load when you’re in trouble

If you lose half of your machinesyou’re doing well if you’re serving half of your traffic

Measure Everything

p(! vs p((

CultureAlways do a post-mortemRelease oftenControl and Responsibility

Facebook Platform

Lessons LearnedFederate everythingKeep failures containedMeasure distributionsUnderstand every problemMake a person responsible

(c) $!!( Facebook, Inc. or its licensors. )"Facebook" is a registered trademark of Facebook, Inc.. All rights reserved. #.!