The document discusses Windows Azure and Platform as a Service (PaaS). It describes the key components including the Fabric Controller which manages hardware resources and the lifecycle of applications. It explains how to deploy a service by uploading the service model and configuration. The process of updating a service through rolling upgrades without downtime is also outlined. Host operating system upgrades are automated to ensure applications are kept up to date without impacting availability. Health monitoring is done through heartbeats to quickly detect and recover from any issues.

1. C# Corner Kolkata presents

2.  Nitesh Luharuka
 Kolkata,IN
 //Website/Blog Goes here//
 MVP and Lead at C# Corner
 Focus on web
 …
 //Contact//

3.  Introduction to C# corner Kolkata Chapter
and Leader
 //Chapter Description Goes here//

4.  Sumantro
 Kolkata,In
 C# Corner Kolkata [Chapter Executive]
 Microsoft SpecialistC#,HTML5,CSS3,JS
 eloquentlyfoss3d.blogspot.com
 Saggy.zone@gmail.com

5.  Windows Azure 101
 The Fabric Controller
 Deploying a service
 Updating a service
 Host OS upgrades

6. A quick introduction

7.  Consumer view:
 On-demand
 Self-service
 Pay-for-use
 Scalable
 + Service provider
view:
 Multi-tenant
 Cost-effective
 What you get?
 Anything the service
provider has to offer!
▪ Compute
▪ Storage
▪ CDN
▪ Integration
▪ VPN
▪ ...
 Resources

8. = Managed forYou Standalone
Servers
IaaS PaaS SaaS
Applications
Runtimes
Database
Operating System
Virtualization
Server
Storage
Networking
Windows Azure
Standardization & Efficiency
Customization & Control

10.  Windows Azure is an OS for the data center
 Takes care of the machine = data center
 You concentrate on business logic
▪ Not on fail-over clustering, provisioning, load balancing, ...
 Provides shared pool of compute, disk and
network
 Illusion of unlimited capacity
 Provides building blocks for applications

11.  Automated OS updates & patches
 Automated application updates
 Automated configuration changes
 Designed to scale out

12.  You should
 Design for costs
 Design for scale out (instead of scale up)
 Design for failure
▪ Idempotent operations
▪ Short timeouts & retries
▪ Stateless (with state on durable storage)

13.  Application consists of
 Actual application in one or multiple roles
▪ Role = isolation boundary (~= DLL)
 Service model
▪ ITPro-as-an-XML
 Configuration

14.  Defines
 Which roles there are
 Role names & types
 VM size (x-small, small, medium, ...)
 Network endpoints required
 What configuration values to expect
 # update domains
 Can not be changed for a deployment

15.  Contains
 # instances
 Configuration values
 Certificates
 …
 Can be changed at runtime

16. Front-
End-2
Middle
Tier-2
Front-
End-1
Middle
Tier-1 Ensure service stays up
during updates
 Update domains =
percentage of service that
will be offline
 Default and max is 5
 Can be overridden
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

17.  Similar to upgrade
domains
 “Unit of failure”
 Considered byWA when
provisioning
 >= 2 fault domains per
service
Front-
End-1
Fault
Domain 1
(eg 1 rack)
Fault
Domain 2
(eg 1 rack)
Front-
End-2
Middle
Tier-2
Middle
Tier-1
Fault
Domain 3
(eg 1 rack)
Middle
Tier-3

18. Your
Service
L
B
L
B
D
N
S
Fabric
Controller
Web Portal
(API)
Model
DNSconfig
ServiceServiceService

19. WindowsAzure’s kernel

20.  Windows Azure kernel
 Manages hardware &
services
 Uses description of
hardware & network
resources it will control
 Service model and
binaries for applications
 Responsibilities
 Resource allocation
 Resource provisioning
 Service lifecycle & health
management
Server Datacenter

21. TOR
LB LB
Agg
PDU
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
…… …
Top of Rack
Switches
Power Distribution
Units
…
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes
Nodes

23.  Distributed application running
on nodes spread across fault domains
 Installed by “Utility” FC
 One primary FC
 Supports rolling upgrade
 If FC fails, your apps are
unaffected

24. Node
Windows
Azure
OS
FC
Host
Agent
Windows Azure Hypervisor
 Power on node
 Network (PXE) boot
of Maintenance OS (WinPE)
 Agent formats disk
& downloads Host OS
 Host OS boots,
runs Sysprep & reboots
 FC connects with
the Host Agent
Fabric Controller
Role
Images
Role
Images
Role
Images
Role
Images
Image Repository
Maintenanc
e OS
Parent
OS
Maintenance
OS
PXE
Server
Windows
Azure
OS

25. 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
27

26. What happens when I click “Upload”?

27.  Process service model files
 Determine resource requirements
 Create role images
 Allocate compute and network resources
 Prepare nodes
 Place role images on nodes
 Create & startVM
 Configure networking
 Dynamic IP addresses (DIPs) assigned to blades
 Virtual IP addresses (VIPs) + ports allocated
 Programs load balancers to allow traffic

28.  Goals:
 Allocate service components to available
resources
 Satisfy constraints (VM size, fault domains)
 Optionally: satisfy soft constraints
 Prefer simplified deployments
▪ Instances from same update domain on same host
 Optimize networking
▪ Put nodes closer together

29. Role B
Count: 2
Update Domains: 2
Fault Domains: 2
Size: Medium
Role A
Count: 3
Update Domains: 3
Fault Domains: 3
Size: Large
LB
my.cloudapp.net

30.  FC pushes role files & configuration to host
agent
 Host agent creates threeVHDs:
 DifferencingVHD for OS image (D:)
▪ Host agent injects FC guest agent intoVHD for Web/Worker
roles
 ResourceVHD for temporary files (C:)
 RoleVHD for role files (first available drive letter e.g.
E:, F:)
 Host agent createsVM, attachesVHDs, and
startsVM

31.  Guest agent starts role host & calls role entry
point
 Starts health heartbeat to and gets commands
from host agent
 Load balancer only routes to external
endpoint when it responds to simple HTTP
GET (LB probe)

32. DEMOLet’s get some evidence...

33. What happens when I click “Upgrade”?

34.  SwapVirtual IPs between the two slots
 Production becomes Staging
 Staging becomes Production
 Instances are not affected
 DNS and LB remains intact
 Happens very fast
 Can only use when the service model hasn’t
changed

35. Load Balancer:
Stage
Prod
Worker Role
VM
Worker Role
VM
VM
VM

36.  “Rolling upgrades”
 Difficult to do in traditional IT
 Leverages Upgrade Domains
 Service model must be identical
 No new roles, no changes in .csdef, etc.
 For Each Upgrade Domain
 Stop instances
 Update
 Start instances

37. Load Balancer
Worker Role Worker Role
#1
#2
#1
#2

38. What happens on “patchTuesday”?

39.  Initiated by theWindows Azure team
 Goal: update all machines ASAP not violating SLA
 Your role instance keeps the sameVM andVHDs,
preserving cached data in the resource volume.
 Update domains are allocated to 1 host node
 Don’t make things confusing
 Allows rebooting a complete host without violating SLA
 Allows updating all hosts for UDx at once

40. What happens when nothing happens?

41.  LB “probes” guest agent every 15 seconds
 Miss 2 probes? LB stops forwarding traffic
 Role can report “busy” to guest agent
 Guest agent stops responding probes
public class WebRole : RoleEntryPoint {
public override bool OnStart() {
RoleEnvironment.StatusCheck += (sender, args) =>
{
if (DateTime.UtcNow.Second > 20)
args.SetBusy();
};
return base.OnStart();
}
}

42.  Based on heartbeats, typically 15
seconds
 Used for status and recovery
 Health state sampler resets the index on
successful poll
 Once index falls below zero, FC attempts
to heal node
 Host agent timeout is 10 minutes
 Worst-case reaction time is timeout
interval + heartbeat interval
Missed
Heartbeat
Recovery
Initiated

43. Application
VM level
Host level
Datacenter
level
Fabric
Controller
Host Agent
Guest
Agent
Your
application
Load
Balancer

44.  Similar to a service update
 Source node:
 Role instances stopped
 VMs stopped
 Node reprovisioned
 Destination node:
 Same steps as initial role instance deployment
 Warning: ResourceVHD is not moved
 (that’s why you should consider it volatile)

45. What to remember?

46.  Windows Azure & PaaS
 The Fabric Controller
 Deploying a service
 Updating a service
 Host OS upgrades
 Health