How Uber Uses your Phone as a Backup Datacenter

Ok

Alright every body so let's dive in

so

let's talk about how Uber trips even happen

Before we get into the nitty gritty of how

we save them from the clutches of the datacenter failover

So you might have heard all about connecting riders and drivers

This is what it looks like

You've probably at least seen the rider app

You get it out you see some cars on the map

You pick where you want to get a pick up location

At the same time, all these guys that you're

seeing on the map.

They have a phone open somewhere.

They're logged in waiting for dispatch

They're all pinging into the same datacenter for the city that you both are in

So then what happens is you put that pin in somewhere

you get ready to pick up your trip, get ready to request

You hit request and
that guy's phone starts beeping

Hopefully if everything works out
He'll accept that trip

All these things that we're talking about
here, the request of a trip

the offering of it to a driver, him
accepting it.

That's something we call a state change
transition

From the moment you start requesting the trip

We start creating your trip data
in the backend datacenter

And that transaction that might live
for anything like 5, 10, 15, 20 however

many minutes it takes you to take your trip

We have to consistently handle that trip

to get it all the way through to completion
to get you where you're going happily

So every time this state change happens

Things happen in the world, so next up
he goes ahead and shows up to you

He arrives, you get in the car,
he begins the trip

Everything is going fine

So this is of course,
So some of these state changes

are more or less important to everything
that's going on

The begin trip and the end trip are the
real important ones

that we don't want to lose the most.

But all these are really important to keep on to

So what happens in the sense of failure is
your trip is gone.

You're both back to
"OMG where'd my trip go"

There you're just seeing empty cars again
and he's back into an open thing

like where you were when you
started/opened the application

in the first place

So this is what used to happen for us
not to long ago

So how do we fix this
how do you fix this in general?

So classically you might try
and say well,

Let's take all the data in that one datacenter
and copy it replicate it to a

backup data center