Automated, Consistent

Application Updates

Updates to the application occur in an automated way

Updates result in clean components forcing consistency

Local storage and OS are left untouched

Automated, Consistent

Configuration Changes

Updates to the settings occur in an automated way

Updates result in clean settings

Local storage and OS are left untouched

Multi-Instance

Management

Identical instances are deployed across the service

Large scale-out services are guaranteed to be consistent

No configuration drift

Scale-out Application scale-out can occur automatically

High Availability The application has no downtime, even in the face of hardware

failures.

Automated, Consistent

OS Servicing

The OS system hosting the application can be updated with the

most recent patches in a coordinated and automated way.

Single Instance

Persistent OS

Single Instance

Stateless OS

Multi-Instance

Stateless OS

Automated, Consistent

Application Updates

Automated, Consistent

Configuration Changes

Multi-Instance Management

Scale-out

High Availability

Automated, Consistent OS

Servicing

Windows Azure

Single Instance

Persistent OS

Single Instance

Stateless OS

Multi-Instance

Stateless OS

Automated, Consistent

Application Updates

Automated, Consistent

Configuration Changes

Multi-Instance Management

Scale-out

High Availability

Automated, Consistent OS

Servicing

Front-End

Front-End

Front-

End-1

Front-

End-2

Update

Domain 1

Update

Domain 2

Middle

Tier-1

Middle

Tier-2

Middle

Tier-3

Update

Domain 3

Middle

Tier-3

Front-

End-2

Front-

End-1

Middle

Tier-2

Middle

Tier-1

Front-

End-1

Front-

End-2

Middle

Tier-2

Middle

Tier-1 Middle

Tier-3

Mark’s Service

Role: Front-End

Definition

Type: Web

VM Size: Small

Endpoints: External-1

Configuration

Instances: 2

Update Domains: 2

Fault Domains: 2

US-North Central Datacenter

FC

Server Datacenter

TOR

LB LB Agg

PDU

LB LB Agg

LB LB Agg

LB LB Agg

LB LB Agg

LB LB Agg

Racks

Datacenter

Routers

Aggregation

Routers and

Load Balancers

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

TOR

PDU

… … … … …

Top of Rack

Switches

Power Distribution

Units

…

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

No

des

Fabric Controller

Role

Images

Role

Images

Role

Images

Role

Images

Image Repository

Maintenance OS Parent

OS

Node

PXE

Server Maintenance OS

Windows Azure

OS

Windows

Azure

OS

FC

Host

Agent

Windows Azure Hypervisor

Fabric Controller (Primary)

FC Host Agent

(trusted)

Host Partition

Guest

Partition

Guest

Agent

Guest

Partition

Guest

Agent

Guest

Partition

Guest

Agent

Guest

Partition

Guest

Agent

Physical Node

Fabric Controller (Replica) Fabric Controller (Replica) …

Role

Instance

Role

Instance

Role

Instance

Role

Instance

Trust boundary

23

Role B Count: 2

Update Domains: 2

Fault Domains: 2

Size: Medium

Role A Count: 3

Update Domains: 2

Fault Domains: 2

Size: Large

Load

Balancer

www.mycloudapp.net

www.mycloudapp.net

Resource Volume

OS Volume

Role Volume

Guest Agent

Role Host

Role Entry Point

Role A

UD 1

Role A

UD 2

Role B

UD 1

Role B

UD 2

Role A

UD 1

Role B

UD 1

Role A

UD 2

Role B

UD 2

Role A

UD 1

Role A

UD 2

Role B

UD 1

Role B

UD 2

Role A

UD 1

Role A

UD 2

Role B

UD 1

Role B

UD 2

• Allocation 1 allows for

2 nodes rebooting

simultaneously

• Host OS upgrade

rollout is 2x faster

with allocation 1

Allocation 1

Allocation 2

Service A

Role A-1

UD 2

Service B

Role A-1

UD 2

Service A

Role B-2

UD 2

Service B

Role B-2

UD 2

Service A

Role A-1

UD 2

Service A

Role B-2

UD 2

Service B

Role B-2

UD 2

Service B

Role A-1

UD 2

Problem How Detected Fabric Response

Role instance crashes FC guest agent monitors role termination FC restarts role

Guest VM or agent crashes FC host agent notices missing guest agent heartbeats

FC restarts VM and hosted role

Host OS or agent crashes FC notices missing host agent heartbeat Tries to recover node FC reallocates roles to other nodes

Detected node hardware issue Host agent informs FC FC migrates roles to other nodes Marks node “out for repair”

25 min

Guest

Agent

Connect

Timeout

Guest Agent

Heartbeat

5s

Role

Instance

Launch

Indefinite

Role

Instance

Start

Role

Instance

Ready

(for updates only)

15 min

Role Instance

Heartbeat

15s

Guest Agent

Heartbeat Timeout

10 min

Role Instance

“Unresponsive” Timeout

30s

Load Balancer

Heartbeat

15s

Load Balancer

Timeout

30s

Guest Agent

Role Instance