Cloud Computing Ch 1

Cloud Computing

a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

Multi-Tenancy

allow multiple users to be served by the same physical hardware.

Scalability

the ability of a cloud computing system to handle growing workloads and resources efficiently without compromising performance

Measured Service / Pay-Per-Use

a pricing model in cloud computing where customers pay only for the computing resources they actually use, typically measured by consumption metrics such as bandwidth, storage, and processing power.

Economies of Scale

the cost advantages obtained due to the scale of operation, with cost per unit of output generally decreasing with increasing scale as fixed costs are spread out over more units of output.

Virtual Multi-Tenancy

computing and storage resources are shared among multiple users

Organic Multi-Tenancy

every component in the system is shared among multiple tenants

Software as a Service

(SaaS) is a cloud computing model that delivers software applications over the internet, allowing users to access programs on a subscription basis without the need for local installation.

ex. Salesforce, MS 365, Facebook

Platform as a Service

(PaaS) is a cloud computing service model that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure

ex. Google App Engine, Microsoft Azure PaaS, Github

Infrastructure as a Service

(IaaS) is a cloud computing model that delivers virtualized computing resources over the internet, allowing users to rent servers, storage, and networking on a pay-as-you-go basis.

ex.Google Compute Engine, Microsoft Azure IaaS, Amazon EC2

Cloud Deployment Models

Public cloud, private cloud, community cloud, hybrid cloud

Public cloud

Available for public use or a large industry group

Private cloud

Operated for exclusive use of a single organization (customer/tenant)

Community cloud

Available for shared use of several organizations supporting a specific community that have similar requirements, goals, security concerns, etc.

Hybrid Cloud

Combines multiple clouds (public and private) that remain unique but bound together to offer application and data portability

Virtualization

refers to the partitioning the resources of a physical system (such as computing, storage, network and memory) into multiple virtual resources

In cloud computing, resources are pooled to serve multiple users using

multi-tenancy

Hypervisor

software that enables virtualization

virtualization layer consists of a hypervisor or a

virtual machine monitor (VMM)

Type 1 Hypervisor

native hypervisors run directly on the host hardware and control the hardware and monitor the guest operating systems.

E.g. VMware ESXi, Microsoft Hyper-V

Type 2 Hypervisor

hosted hypervisors run on top of a conventional (main/host) operating system and monitor the guest operating systems.

E.g. VMware Workstation, Oracle VirtualBox

Full virtualization

the virtualization layer completely decouples the guest OS from the underlying hardware.

The guest OS requires no modification and is not aware that it is being virtualized.

Full virtualization is enabled by direct execution of user requests and binary translation of OS requests.

Para Virtualization

the guest OS is modified to enable communication with the hypervisor to improve performance and efficiency.

The guest OS kernel is modified to replace non-virtualizable instructions with hyper-calls that communicate directly with the virtualization layer hypervisor

Hardware virtualization

enabled by hardware features such as Intel’s Virtualization Technology (VT-x) and AMD’s AMD-V.

In hardware assisted virtualization, privileged and sensitive calls are set to automatically trap to the hypervisor.

Thus, there is no need for either binary translation or para-virtualization.

Load balancing

distributes workloads uniformly across multiple servers to meet the application workloads

Weighted round robin load balancing

more powerful users handle more requests

Low latency load balancing

incoming request is routed to the server with the lowest latency

Least connections load balancing

incoming request is routed to the server with the least number of connections

Priority load balancing

each server is assigned a priority, incoming request is routed to the highest priority server as long as the server is available/up

Overflow load balancing

when request to the highest priority server overflows, only then requests are routed to the lower priority server

Load balancing persistence approaches

sticky sessions, session database, browser cookies, URL rewriting

Sticky session

all the requests belonging to a user session (user preferences, configurations, etc.) are routed to the same server

Session database

all the session info is stored in an external session database

Browser cookies

session data is stored in browser cookies

URL rewriting

a URL re-write engine stores the session info by modifying the URLs on the client side

Capacity planning involves

the right-sizing of each tier of the deployment of an application in terms of the number of resources and the capacity of each resource

Vertical scaling/scaling up

Involves upgrading the hardware resources (adding additional computing, memory, storage or network resources).

Horizontal scaling/scaling out

Involves addition of more resources of the same type

Cloud application deployment design is an iterative process that involves

deployment design, performance evaluation, and deployment refinement

Deployment Design

The variables in this step include the number of servers (app/web/database servers) in each tier, computing, memory and storage capacities of servers, server interconnection, load balancing and replication strategies

Performance evaluation

To verify whether the application meets the performance requirements with the deployment

Involves monitoring the workload on the application and measuring various workload parameters such as response time (latency: P90, P95, P99) and throughput (bits/sec).

Utilization of servers (CPU, memory, disk, I/O, etc.) in each tier is also monitored

Deployment refinement

Various alternatives can exist in this step such as vertical scaling (or scaling up), horizontal scaling (or scaling out), alternative server interconnections, alternative load balancing and replication strategies, for instance

Replication

used to create and maintain multiple copies of the data in the cloud

Cloud enables rapid implementation of replication solutions for

disaster recovery

Types of replication

array-based, network-based, host-based

Array-based replication

uses NAS, SAN to replicate; require similar arrays at local and remote locations

Network-based replication

uses an appliance to replicate, supports heterogeneous environments

Host-based replication

use software/agents to transfer data from a local host to a remote host

Monitoring services allow cloud users to

collect and analyze the data on various monitoring metrics

Software-define networking (SDN)

a networking architecture that separates the control plane (an SDN Controller) from the data plane (network devices like switches and routers) and centralizes the network controller

Conventional network architecture

The control plane and data plane are coupled

Control plane

the part of the network that carries the signaling and routing message traffic

Data plane

part of the network that carries the payload data traffic

SDN architecture

The control and data planes are decoupled and the network controller is centralized

SDN key elements

centralized network controller

programmable open APIs

Standard communication interface (OpenFlow)

OpenFlow

the broadly accepted SDN protocol for the southbound interface

With open flow, the forwarding plane of the network devices (switch, router, etc), can be …

directly accessed and manipulated

Network functions virtualization (NFV)

a technology that leverages virtualization to consolidate the heterogeneous network devices onto industry standard high volume servers, switches and storage.

examples of network functions are routing, firewalling, load balancing, etc

NFV relationship to SDN

NFV is complementary to SDN as NFV can provide the infrastructure on which SDN can run

NFV and SDN are mutually beneficial to each other but not dependent

Network functions (e.g., firewalls, load balancers, routers) can be virtualized without SDN, similarly, SDN can run without NFV

Key elements of NFV architecture

virtualized network function (VNF)

NFV infrastructure (NFVI)

NFV management and orchestration

MapReduce

a parallel data processing model for processing and analysis of massive scale data

MapReduce phases

map phase, reduce phase

Map phase

data is read from a distributed file system, partitioned among a set of computing nodes in the cluster, and sent to the nodes as a set of key-value pairs

Reduce phase

When all the Map tasks are completed, the Reduce phase begins in which the intermediate data with the same key is aggregated

Identity and access management (IDAM) (for cloud)

describes the authentication and authorization of users to provide secure access to cloud resources

Cloud service providers (CSPs) offer 3 billing models:

Elastic pricing

Fixed pricing

Spot pricing

Elastic pricing

or pay-as-you-go pricing model, the customers are charged based on the usage of cloud resources

Fixed pricing

customers are charged a fixed amount per month for the cloud resources

Spot pricing

offer variable pricing for cloud resources which is driven by market demand

Cloud reference model

Infrastructure and facilities layer

Hardware layer

Virtualization layer

Platform and middleware layer

Service management layer

Applications layer

Compute services

provide dynamically scalable compute capacity in the cloud

Compute resources can be provisioned on-demand in the form of

virtual machines

VMs can be created from

standard images (e.g. AMI) provided by the cloud service provider or custom images created by the users

Compute service provided by Amazon

Amazon Elastic Compute Cloud (EC2)

Cloud storage services

allow storage and retrieval of any amount of data, at any time from anywhere on the web

Most cloud storage services organize data into

buckets or containers

Cloud storage services provide

Scalability

Replication

Access policies

Encryption

Consistency

an online cloud-based data storage infrastructure for storing and retrieving any amount of data

Amazon Simple Storage Service (S3)

a web service that makes it easy to setup, operate and scale a relational database in the cloud

Amazon relational database service (RDS)

the non-relational (No-SQL) database service from Amazon

Amazon DynamoDB

DynamoDB model includes

tables, items, and attributes

DynamoDB is a __________ that automatically spreads the data and traffic for the stored tables over a number of servers to meet the throughput requirements specified by the users

fully managed service

____allow developers to develop and host applications in the cloud.

Cloud based application runtimes and frameworks

queuing service from Amazon

Amazon Simple Queue Service (SQS)

SQS attributes

short messages

multiple readers/writers

high availability

Cloud-based email service

Amazon simple email service (SES)

SES is an ___ email-sending service

outbound only

(no reply emails)

SES service can be accessed and used from

the SES console

SMTP interface

SES API

push messaging service from Amazon

Amazon Simple notification service (SNS)

SNS has two types of clients

publishers

subscribers

Publishers communicate ___ with subscribers by producing and sending messages to topics. A topic is ___

asynchronously

a logical access point and communication channel

SNS can deliver notifications as

SMS

email

SQS queues

any HTTP endpoint

__ is a cloud-based video transcoding service from Amazon

Amazon Elastic transcoder

Content Delivery Networks (CDNs)

a distributed system of servers located across multiple geographic locations to serve content to end-users with high availability and high performance (high throughput and low latency)

Amazon CloudFront

a content delivery service from Amazon. CloudFront can be used to deliver dynamic, static and streaming content using a global network of edge locations

Amazon Elastic MapReduce (EMR)

the MapReduce service from Amazon based on the Hadoop framework running on Amazon EC2 and S3

Amazon Elastic Beanstalk

allows you to quickly deploy and manage applications in the AWS cloud

Amazon CloudFormation

a deployment management service from Amazon

Identity & Access Management (IDAM)

allow managing the authentication and authorization of users to provide secure access to cloud resources and services

AWS Identity and Access Management (IAM)

allows you to manage users and user permissions for an AWS account