What is IaaS? A practical guide to understanding the differences between SaaS and PaaS and what you need to do in-house

When considering cloud services, you may find yourself unable to make a decision without clarifying points such as "What is IaaS?", "How is it different from SaaS and PaaS?", and "To what extent will your company need to handle the workload itself if you choose IaaS?"

IaaS is a system that allows you to use IT infrastructure such as servers, storage, and networks on the cloud as much as you need. While it offers a high degree of freedom, the design, configuration, and operation of the OS and beyond are left to the user. If you choose IaaS without understanding these assumptions, you are likely to encounter discrepancies in operational load and costs.

In this article, we will clarify the basic definition of IaaS and explain the differences between SaaS, PaaS, and IaaS from the perspective of the scope of services provided and the tasks performed by users. We will also outline the requirements for IaaS, points to note, and criteria for comparison.

What is IaaS?

It's important to understand that IaaS does not mean "cloud = a system where you can leave everything to us." While IaaS allows you to use IT infrastructure flexibly, if you don't correctly understand what the cloud provider is responsible for and what the user is responsible for, you are likely to incur unexpected burdens in terms of operations and costs.

Definition of IaaS

IaaS (Infrastructure as a Service) is a form of cloud service that makes IT infrastructure such as servers, storage, and networks available via the Internet. Rather than owning and managing physical servers and network equipment in-house, you rent and use only the infrastructure resources you need.

A key feature of this service is that users can freely build their own operating systems, middleware, and applications on top of the infrastructure provided.

Scope of infrastructure provided by IaaS

IaaS mainly provides the following infrastructure:

• Server: Computing resources (CPU and memory) provided as virtual machines

• Storage: Disk space for storing data (block storage, object storage, etc.)

• Network: Virtual networks, IP addresses, load balancers, etc.

They can be flexibly created and modified through a management screen or API, and charges are generally based on usage. However, in principle, the user is responsible for OS configuration, middleware installation, monitoring and backup design, etc.

Differences from on-premise

In an on-premise environment, you purchase and install your own servers and network equipment, and also perform maintenance and updates yourself. This requires a large initial investment, and expansion or contraction takes time.

With IaaS, the cloud provider is responsible for managing physical facilities, allowing users to focus on logical infrastructure design and operation. The difference is that the required resources can be increased or decreased in a short amount of time, and capital investment can be reduced. However, mistakes in operational design and cost management can result in a heavier burden than on-premise systems, so it is important to clearly define the division of roles before implementation.

What users are responsible for and what vendors are responsible for in IaaS

IaaS is a service that allows you to use infrastructure in the cloud, but it does not mean that you can leave everything to them. If you do not understand what is the vendor's responsibility and what is yours, unexpected problems will arise in terms of operational burden and costs after implementation.

Overall scope of responsibility

In IaaS, the cloud provider is responsible for the physical infrastructure layer, specifically the maintenance and management of data centers, physical servers, storage devices, and network devices.

On the other hand, the OS, middleware, applications, and data built on top of it are the responsibility of the user. Because IaaS offers a high degree of freedom, users must decide for themselves how to design and operate each layer. This is what makes it different from SaaS and PaaS.

Main tasks required by the user

When using IaaS, the user must perform the following tasks:

• OS configuration and updates: OS installation, patch application, version management

• Middleware management: installation and configuration of web servers, databases, runtimes, etc.

• Monitoring and fault response: resource monitoring, alert settings, and first response when a fault occurs

• Backup design: acquisition method, generation management, and recovery procedure

• Security measures: access control, network settings, vulnerability countermeasures

It is possible to reduce the burden by utilizing the functions and managed services provided by cloud providers, but this does not mean that you will be in a state where you do not have to do anything.

Common stumbling points after introducing IaaS

One common stumbling block after implementing IaaS is when operational design is postponed. Even if construction goes smoothly, the load can suddenly increase during the operational phase if systems for monitoring, backup, and fault response are not in place.

In addition, there are many cases where confusion arises due to a lack of understanding of the scope of responsibility, with people saying things like, "I thought the vendor would handle it," or "I don't know to what extent my company will handle it."

The differences between SaaS, PaaS, and IaaS

When comparing cloud services, the three that are often listed are SaaS, PaaS, and IaaS. Although they all share the same "cloud" framework, the scope of what is provided and the roles that users play differ.

Fundamental differences between the three service models

The difference between SaaS, PaaS, and IaaS lies in what the cloud provider provides and where the user takes responsibility.

• SaaS (Software as a Service)

  • This is a form in which the application itself is used. Users can concentrate on configuration and operation, and there is little need to be concerned with managing infrastructure, OS, or middleware.

• PaaS (Platform as a Service)

  • The execution environment (OS, middleware, runtime, etc.) required to run the application is provided. Users can focus on developing and running their applications, but there are certain restrictions on the platform specifications.

• Infrastructure as a Service

  • Only infrastructure such as servers, storage, and networks are provided. While the user can freely design everything from the OS onwards, the responsibility for building and operating the system rests with the user.

Comparison of scope and flexibility

The wider the scope of service provided, the lighter the operational burden on users, but the less freedom they have.

Conversely, the narrower the scope of services offered, the greater the degree of freedom, but the greater the operational responsibility.

• SaaS: Less flexibility, but the least operational burden

• PaaS: Balanced flexibility and operational load

• IaaS: Highest degree of freedom, but also a heavy operational burden

By understanding this relationship, you can avoid the risk of choosing an IaaS service based solely on impressions such as "it seems highly functional" or "it seems flexible."

In what order should you consider them (SaaS → PaaS → IaaS)?

When considering cloud adoption, it's important not to jump straight into IaaS. The basic order is to first check whether SaaS can meet your requirements, then consider PaaS, and if that's still not enough, consider IaaS.

By thinking in this order, you can avoid mistakes such as "SaaS would have been sufficient, but we chose IaaS and ended up taking on an operational burden."

Benefits of IaaS

The biggest feature of IaaS is that it offers a high degree of freedom in infrastructure design, even though it is a cloud service. Areas that tend to be constrained by SaaS and PaaS can be flexibly designed to suit your company's requirements, making it a strong choice for systems that must meet specific conditions.

High degree of freedom in infrastructure design

With IaaS, you can choose the OS type and version, middleware configuration, network design, etc. It is also possible to bring in a design similar to an on-premise environment as is, making it easy to migrate existing systems or to accommodate special requirements.

The flexibility of IaaS is an advantage in cases where business systems require specific middleware or version specifications, or where unique network configurations are required.

Resources can be increased or decreased flexibly

The number of servers and resources such as CPU and memory can be increased or decreased in a short time as needed. This allows adjustments to be made in response to increases in access and fluctuations in processing volume, eliminating the need for excessive capital investment to accommodate peak times.

The advantage is that resources can be flexibly controlled in systems where there is a large difference between busy and slow periods, or in testing environments where the load temporarily increases.

Easy to design BCP/DR measures

It is relatively easy to design a configuration that utilizes multiple locations and multiple regions. Because backup and standby systems can be placed in physically separate environments, it is easy to incorporate recovery plans (BCP/DR) in the event of a disaster or failure.

Redundant configurations and remote backups, which tend to be costly on-premises, can be easily implemented in stages with IaaS, allowing you to consider designs that assume business continuity at a realistic cost.

Disadvantages and points to note about IaaS

While IaaS offers a high degree of freedom, it also comes with a correspondingly greater responsibility and burden on the user. If you judge it solely on the benefits, you may encounter unexpected challenges in terms of operation and costs after implementation.

Operation and maintenance burdens are incurred

Users must manage the OS and middleware, monitor it, and troubleshoot issues. Setting up a server is easy, but if the subsequent operational design is insufficient, a lot of time will be spent on daily maintenance and troubleshooting.

In organizations with limited personnel or little experience in infrastructure operations, operations tend to be personalized and become an ongoing burden.

Factors that can cause costs to increase more than expected

IaaS is based on pay-as-you-go pricing, but it doesn't necessarily mean that the more you use the cheaper it becomes. If you keep your servers running all the time, allocate more specs than necessary, or keep increasing the amount of backups and logs, your costs will gradually increase.

If you don't take into account the amount of data transferred, redundant configuration, and labor costs for monitoring and operation, it may end up being more expensive than on-premises.

Security depends on configuration and operation

With IaaS, the cloud provider is responsible for the security of the physical infrastructure, but the user is responsible for the OS, network settings, access control, etc. Misconfigurations or inadequate operational rules increase the risk of information leaks and unauthorized access.

Rather than assuming that "it's safe because it's cloud," the premise is to understand what areas your company needs to protect and then carry out continuous security operations.

Cases where IaaS is suitable/unsuitable

IaaS is not suitable for all systems or business processes, so it is important to select it after sorting out whether it suits your company's requirements and structure.

Requirements and tasks for which IaaS is suitable

IaaS is suitable when a certain degree of freedom is required in infrastructure configuration and operation.

• Business systems where you want to specify the type and version of the OS or middleware

• If you want to migrate your existing on-premises environment without making major changes to the configuration

• Systems with unique network designs and security requirements

• Operations where the processing load fluctuates greatly and you want to be able to flexibly increase or decrease resources

• When you want to design a redundant configuration based on BCP/DR

When these requirements are met, SaaS and PaaS have many restrictions, making the flexibility of IaaS more effective.

When is SaaS or PaaS a better fit?

On the other hand, the benefits of choosing IaaS are less in the following cases:

• Standard business operations with few customization requirements

• When there are no personnel or systems capable of operating the infrastructure

• When you want to reduce the operational load as much as possible

• When you want to prioritize speed of development and operation

In such cases, choosing SaaS or PaaS often makes more sense in terms of cost and operation.

What to do when you're unsure of what to do

If you are unsure which option to choose, it is effective to start by asking yourself, "Are there any requirements that can only be met with IaaS?" You can first consider SaaS, then PaaS, and if that does not meet your requirements, choose IaaS.

Typical IaaS service concepts

When comparing IaaS services, it is easier to make a decision if you understand the position of each service rather than listing the specifications of each individual service in detail. This is because usability of IaaS depends not on differences in functionality but on the ecosystem, operational philosophy, and combination with peripheral services.

Major IaaS Positioning

The following are the positions of representative IaaS services used globally.

• Amazon Web Services (AWS)

  • It features a huge number of services and a wide range of options, from infrastructure to managed services. Starting with IaaS, it is structured to be easily expandable in stages, including PaaS-like usage and serverless.

• Microsoft Azure

  • It has high compatibility with Microsoft products such as Windows Server and Active Directory, and tends to be chosen in cases where integration with existing internal IT environments is important.

• Google Cloud (GCP)

  • This service has strengths in data analysis and container-related technologies, and is often adopted in systems that assume a cloud-native configuration.

All of them offer IaaS, but they have different areas of expertise and the comprehensiveness of related services, so your choice will depend on what you prioritize as IaaS.

Conditions suitable for domestic IaaS

IaaS provided by domestic providers may be considered under the following conditions:

• When compliance with domestic laws and regulations and industry guidelines is important

• If you want support in Japanese and easy-to-understand contract terms

• Systems that require closed network connections or cooperation with existing lines

• Business systems that do not require the use of overseas regions

The number of services may be limited compared to global IaaS, but depending on your requirements, it can be an option that provides peace of mind in terms of operations.

IaaS and related technologies

IaaS is not a standalone technology, but is generally used in combination with related technologies.

• VM (Virtual Machine)

  • This is the basic form of IaaS, and is a method that makes it easy to migrate a configuration that is close to on-premise.

• コ ン テ ナ

  • By building a container infrastructure on IaaS, you can streamline management and deployment on an application-by-application basis.

• Serverless

  • It is often used to replace some of the functions of IaaS, and is chosen when you want to further reduce the scope of infrastructure management.

When considering IaaS, it will be easier to review your configuration if you also consider future developments, such as "Should we use only VMs?" or "Should we combine it with containers or serverless in the future?"

Checkpoints when choosing an IaaS

If you decide based solely on functionality and price, you are more likely to encounter problems after implementation, such as "not being able to operate as expected" or "cost management being difficult." We will organize the points you should keep in mind beforehand.

Requirements

First, you need to clarify your system requirements. The IaaS you should choose will vary depending on the required performance, network configuration, and availability level.

• Can you secure enough CPU and memory for the expected processing volume?

• Can you meet network requirements such as fixed IP addresses, closed network connections, and VPNs?

• Is availability design possible, such as redundant configurations and multi-region configurations?

If you make a selection without clarifying your requirements, you may need to change the configuration later, which will increase costs and labor.

Operational structure

With IaaS, the operational structure after construction is important. The services and configurations you should choose will vary depending on whether you operate the system in-house or outsource it.

• Can we handle 24/365 monitoring and troubleshooting in-house?

• If operations are outsourced, to what extent can they be outsourced?

• Have you organized the division of roles and the communication system in the event of a problem?

If the system is not designed with the operational structure in mind, responses to problems will likely be personalized.

Cost and contract terms

When considering IaaS costs, you need to consider not only the usage fee but also the contract terms and operational costs.

• Do you understand the billing units and pay-as-you-go system?

• Are there options for long-term use and reserved discounts?

• Are there any additional support or data transfer fees?

It is important not to compare only the low monthly fee, but to check the total cost including operation and the contract terms before making a decision.

FAQ

What is the difference between IaaS and a rental server?

A rental server is a service that allows you to use a pre-prepared server environment on a shared or exclusive basis. The degree of freedom in configuration and settings is limited, and there are restrictions on expansion and changes. On the other hand, IaaS allows you to combine and use servers, storage, and networks individually, allowing you to flexibly change configurations and resources.

If you prioritize flexibility and scalability, IaaS is the better choice, while if you prioritize ease of use and low operational load, a rental server is the better choice.

To what extent is the user responsible for IaaS?

With IaaS, the vendor is responsible for the infrastructure, such as physical servers and data centers, while the user is responsible for OS configuration and updates, middleware management, applications, data, access control, and so on.

The burden can be reduced by utilizing the security features and managed services provided by cloud providers, but it is important to keep in mind that the user is ultimately responsible for the configuration and operation.

Does IaaS really reduce costs?

IaaS tends to have a high cost-saving effect at the time of implementation because it reduces initial investment. However, continuous operation, excessive resource allocation, and increased backup and data transfer volume can result in operational costs increasing more than expected.

Whether or not this leads to cost reduction depends on resource management and operational design. The key to success is to regularly review usage and ensure that only what is needed is used.

Conclusion

IaaS is a service that allows flexible use of IT infrastructure such as servers, storage, and networks, but the user is responsible for the design and operation of the OS and beyond. If you choose an IaaS service based solely on its flexibility, you may end up with a difference from your expectations in terms of operational load and costs.

The difference between SaaS, PaaS, and IaaS is not the number of functions, but the scope of services provided and the responsibility that lies within. It is important to first check whether SaaS or PaaS can meet your requirements, and if that is not possible, consider IaaS.

When selecting an IaaS, you need to consider not only your company's requirements, but also its operational structure and cost management. By organizing your options based on the premise of "how much your company can handle," you can minimize any gaps after implementation.

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