IaaS (Infrastructure as a Service):
The Ultimate Guide

What is Platform as a Service (PaaS)?

Platform as a Service (PaaS) provides some infrastructure components, along with additional managed service and software. A PaaS is a framework developers can use to create their own applications, focusing on developing software functionality for their end users. The cloud provider manages complex back-end infrastructure, including computing resources, operating systems, software updates, storage, networking, and integrations.

What is Software as a Service (SaaS)?

Software as a service (SaaS) is a popular choice for cloud users. Because SaaS delivers software to end users over the Internet, most SaaS applications run directly from a web browser and do not need to be downloaded or installed by the customer. PaaS, on the other hand, delivers a software development platform. The majority of cloud consumers do not need PaaS.

This web services model eliminates the need for IT staff to download and install applications on local devices. SaaS enables providers to simplify service and support for their business, while solving potential technical problems such as data and storage management, middleware, servers, and networking.

Key Differences Between IaaS, PaaS and SaaS

• PaaS is based on the IaaS model—this is because, in addition to infrastructure components, the provider manages the operating systems, middleware, and other operating environments for cloud users. PaaS workloads simplify deployment but offer more limited flexibility compared to a pure IaaS model.
• SaaS manages all infrastructure and applications needed for the end user—SaaS users don't need to install or deploy anything. They can typically just login and start using the provider's application, running on the provider's infrastructure. Users can customize the behavior of applications, add their own data, and restrict access. Almost all other aspects are the responsibility of the SaaS provider.

AWS High Availability Architecture

Amazon Web Services has built a massive global infrastructure to provide high availability and flexibility for customer workloads.

Amazon offers cloud services in 24 regions (see the map of the Amazon regions). Amazon defines a region as a geographic area with at least three different data centers known as availability zones (AZs).

Each AWS availability zone is a fully localized infrastructure with redundant power supplies, networks, and Internet connectivity. Currently, Amazon supports 77 Availability Zones worldwide. Each AZ typically has three or more data centers in one location, separated by a “meaningful distance” of up to 100 km. This ensures a physical disaster is unlikely to take down all data centers in the AZ, and yet enables high-speed connections between the data centers.

Learn more in our in-depth guide to AWS high availability.

Azure High Availability Architecture

Like AWS, Azure also bases its high availability architecture on regions and availability zones. Azure always stores three copies of user data across three availability zones. This is called redundant local storage. Customers can opt for global redundant storage, to create up to three additional copies of their data in a “paired region”, a nearby region that has fast connectivity with the first region, for added flexibility.

Azure availability zones achieve high availability by distributing resources across multiple data centers in a customer’s region. Azure provides additional services like Azure Site Recovery and Azure Backup to achieve the required recovery point objective (RPO) and recovery time objective (RTO) for their applications. 

Learn more in our in-depth guide to Azure high availability.

Google Cloud SQL High Availability Architecture

In Google Cloud, resources that operate in one zone are called “zonal resources”. Other resources operate across an entire region and are called “regional resources”. For example, a Google Cloud virtual machine instance or persistent disk is a zonal resource, while a static IP address is a regional resource.

Google adds the concept of clusters—clusters are groups of physical computers inside a physical data center, with independent power, cooling, networking, and security infrastructure. This allows Google Compute Engine to balance customer resources across clusters in the same zone, while retaining high connectivity between the physical machines in each cluster.

Amazon S3

Amazon Simple Storage Service (S3) is the first and most popular Amazon service, which provides object storage at unlimited scale. S3 is easy to access via the Internet and programmatically via API, and is integrated into a wide range of applications. It provides 11 9’s of durability (99.999999999%), and offers several storage tiers, allowing users to move data that is used less frequently into a low-cost archive tier within S3. 

Related content: read our guide to mounting S3 as a file system.

AWS EC2

Amazon Elastic Compute Cloud (Amazon EC2) offers scalable computing resources. It lets you run as many virtual servers as you want, configure your network and security, and manage storage. You can increase or decrease resources on-demand according to changing business requirements, and set up auto scaling to scale resources up and down according to actual workloads. 

AWS EBS

Amazon Elastic Block Store (Amazon EBS) is a block-level storage service for use with Amazon EC2 instances. When mounted on an Amazon EC2 instance, you can use Amazon EBS volumes like any other raw block storage device. It can be formatted and mirrored for specific file systems, host operating systems, and applications.

Learn more in our in-depth guide to AWS EBS.

AWS EFS

Amazon Elastic File System (Amazon EFS) provides a simple, scalable, and fully managed elastic NFS file system for use with AWS cloud services and on-premises resources. It can support up to petabytes of data, automatically scaling as files are added and removed, eliminating the need to configure and manage storage capacity.

Learn more in our in-depth guide to AWS EFS.

AWS Lambda

AWS Lambda is a serverless, on-demand IT service that provides developers with a fully managed, event-driven cloud system that executes code. AWS Lambda uses Lambda functions—anonymous functions that are not associated with identifiers—enabling users to package any code into a function and run it, independently of other infrastructure.

Learn more about AWS Lambda and the AWS Serverless ecosystem.

Linux Virtual Machines in Azure

Traditionally Azure focused on Windows virtual machines, but now has a robust offering for Linux users as well. Azure virtual machines (VMs) are scalable on-demand compute resources provided by Azure.

Microsoft Azure supports popular Linux distributions deployed and managed by multiple partners. Linux machine images are available in the Azure Marketplace for the following Linux distributions (more distributions are added on an ongoing basis):

• FreeBSD
• Red Hat Enterprise
• CentOS
• SUSE Linux Enterprise
• Debian
• Ubuntu
• CoreOS
• RancherOS

Azure Files

Azure Files is a cloud file storage service that provides access to server message block (SMB) file shares. These shares can be configured as part of an Azure storage account. Azure Files enables cloud-based virtual machines and on-premise applications to share files using standard protocols.

Learn more in our in-depth guide to Azure Files.

Azure Managed Disk

Azure managed disks are block-level storage volumes managed by Azure and used by Azure virtual machines. A managed disk is similar to a physical disk on a local server, but it is virtualized. For managed disks, you only need to specify the disk size and disk type, and provision—Azure does the rest. The available hard drive types are: 

• Standard hard disks (HDD)
• Standard SSD
• Premium SSDs
• Ultra disks—optimized for sub-millisecond latency

Related content: read our guide to Azure Disk pricing.

Azure Blob Storage

Azure Blob Storage is Microsoft's object storage service, similar to Amazon S3. Blob storage is suitable for storing large amounts of unstructured data. Blob storage offers sixteen 9’s of durability, and advanced security features including RBAC, encryption at rest and advanced threat protection. IT also supports lifecycle management and immutable storage (WORM), which can help protect against data loss and threats like Ransomware. 

Related content: read our guide to Azure Blob Storage pricing.

HPC on Azure

Azure provides high performance computing (HPC) resources, which you can deploy purely on the public cloud, or combine with local HPC resources to create a hybrid HPC deployment. Azure provides an HPC head node which is used to schedule jobs and workloads, and a virtual machine scale set, with large numbers of VMs that can be used to run massively parallel workloads. These VMs can include both CPU and GPU hardware, depending on the type of processing required.

Learn more in our in-depth guide to HPC on Azure.

SAP on Azure

A large variety of SAP applications can be deployed to Azure, using predefined virtual machines created and certified by SAP.

SAP HANA
You can run the SAP HANA in-memory database on Azure, using M-series VMs that scale up to 4TB memory, certified for use with SAP HANA. Another option is Mv2 VMs, the largest SAP HANA certified VMs in the public cloud, with 6TB of memory. Azure offers a service level agreement (SLA) of 99.99% for instances in high availability pairs, and 99.9% for standalone instances.

SAP S/4HANA
You can deploy SAP S/4HANA on Azure, with remote connection via Azure ExpressRoute for Fiori applications. Azure provides an SLA of 99.99% SLA if you run S/4HANA in two Azure availability zones. It also provides backup and recovery in second, even for databases with multiple TBs of data.

VDI on Azure

Microsoft Virtual Desktop Infrastructure (VDI) offers multi-tenant support for Windows 10 and a Windows Virtual Desktop license. Azure provides the FSLogix configuration file container, which decouples user configuration files from the underlying operating system. Azure recently launched MSIX AppAttach, which allows you to package a Win32 application in an MSIX application container.

Google Cloud Storage

Google Cloud Storage is an object storage service by Google Cloud. It provides features like object versioning and extended permissions (per item or bucket). Google Cloud offers two archive storage tiers with lower pricing and fast retrieval times, called Nearline and Coldline.

Learn more about storage options in Google Cloud—lock, network file, and object storage—in our guide to Google Cloud Storage.

Google Cloud Filestore

Google Cloud Filestore uses NFS version 3 and is designed for workloads requiring low latency and minimal performance fluctuations. This service has two levels of performance: standard and premium. The premium tier can support very high performance—700 Mbps for reads, 350 Mbps for writes, and a maximum of IOPS of 30,000.

Google Persistent Disk

In Google Cloud, a Persistent Disk is a storage device that you can access from a virtual machine, like a physical hard drive. The data is spread across multiple physical hard drives in the Google data center. Google Compute Engine manages the distribution of data for optimal redundancy and performance.

Learn more about Google Cloud Persistent Disk: How to Create a Virtual Image with Google Cloud Compute Engine.

Rehosting

Re-hosting (also known as "lift and shift") is the fastest way to move your application to the cloud. This is usually the first approach taken in a cloud migration project, because it allows moving the application to the cloud without any changes. Both physical and virtual servers are migrated to infrastructure as a service (IaaS). Lift and shift is commonly used to improve performance and reliability for legacy applications. 

Learn more in our in-depth guide to lift and shift.

Replatforming, Refactoring, or Re-architecture

This migration strategy involves detailed planning and a high investment, but it is the only strategy that can help you get the most out of the cloud. Applications that undergo replatforming or re-architecture are completely rebuilt on cloud-native infrastructure. They scale up and down on-demand, are portable between cloud resources and even between different cloud providers.

Repurchasing

In most cases, repurchasing is as easy as moving from an on-premise application to a SaaS platform. Typical examples are switching from internal CRM to Salesforce.com, or switching from internal email server to Google’s G Suite. It is a simple license change, which can reduce labor, maintenance, and storage costs for the organization.

Retire

When planning a move to the cloud, it often turns out that part of the company's IT product portfolio is no longer useful and can be decommissioned. Removing old applications allows you to focus time and budget on high priority applications and improve overall productivity.

Retain

Moving to the cloud doesn't make sense for all applications. You need a strong business model to justify migration costs and downtime. Additionally, some industries require strict compliance with laws that prevent data migration to the cloud. Some on-premises solutions should be kept on-premises, and can be supported in a hybrid cloud migration model.