Glossary

Reserved Instances

What are reserved instances?


Reserved Instances (RIs) are a pricing and capacity reservation offering provided by AWS for their EC2 (Elastic Compute Cloud) and RDS (Relational Database Service) services.


They specifically allow users to commit to using a specific instance type in the same region for either a one or three-year term, in exchange for discounts of up to 72% – the exact discount is ultimately dependent on the commitment term, instance type, availability zone and region.


There are various types of Reserved Instances available, each with different terms and levels of flexibility. Standard Reserved Instances provide the highest cost savings but are the least flexible, whereas Convertible Reserved Instances offer more flexibility by allowing you to change instance families within the same instance type.


In contrast, Scheduled Reserved Instances offer a lower discount, but allow you to reserve capacity for specific time windows, such as business hours or weekends, providing cost savings for predictable workloads.

What are reserved instances?


Reserved Instances (RIs) are a pricing and capacity reservation offering provided by AWS for their EC2 (Elastic Compute Cloud) and RDS (Relational Database Service) services.


They specifically allow users to commit to using a specific instance type in the same region for either a one or three-year term, in exchange for discounts of up to 72% – the exact discount is ultimately dependent on the commitment term, instance type, availability zone and region.


There are various types of Reserved Instances available, each with different terms and levels of flexibility. Standard Reserved Instances provide the highest cost savings but are the least flexible, whereas Convertible Reserved Instances offer more flexibility by allowing you to change instance families within the same instance type.


In contrast, Scheduled Reserved Instances offer a lower discount, but allow you to reserve capacity for specific time windows, such as business hours or weekends, providing cost savings for predictable workloads.

Related Definitions

Cloud Instances

What is an instance in the context of cloud computing?


In cloud computing, an instance refers to a virtual server provided by a third-party cloud service, for example AWS, Azure or Google Cloud. These instances ultimately enable companies to deploy and run their applications or services in the cloud, in a scalable and flexible manner. This is because instances are on-demand and can be adjusted based on your workload requirements.

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Zero-Based Budgeting

What is zero-based budgeting?


Zero-based budgeting is an accounting technique that requires all expenses to be justified and approved for each financial period, starting from zero rather than a pre-existing spend. This enables organizations to monitor and assess the necessity of each cost on a more granular level, lowering expenses and promoting fiscal responsibility.


Originally conceived in the 1970s, zero-based budgeting isn’t a new idea — but in the current economic climate, accounting for every dollar is helping businesses to regain control over their outgoings. The technique can be applied to a wide range of costs, from research and development to asset management.

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SaaS Agreement

What is a SaaS agreement?


A SaaS agreement, or contract, details the terms of your purchase from a SaaS vendor.

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Service Level Agreement (SLA)

What is a service level agreement in SaaS?


A Service Level Agreement (SLA) is a subset of a Master Service Agreement (MSA) and contains specific details about the level of service that will be provided by the SaaS vendor. This agreement will specifically define the performance metrics, responsibilities, and expectations of both parties.


An SLA is likely to include uptime guarantees, the level of support that will be provided to the customer, response times for any support requests, information on how these requests will be managed and escalated, information on how the vendor will protect the customer’s data and ensure the security of its systems and networks, as well as details on how it will compensate the customer if it fails to meet the agreed-upon service levels.

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Decentralized Procurement

What is decentralized procurement?


Decentralized purchasing in SaaS refers to the process of allowing individual departments or teams within an organization to make their own purchasing decisions for software applications. This is in contrast to a centralized purchasing model, where all purchasing decisions are approved by a single procurement team or a department such as finance.
While a decentralized purchasing model can provide teams with the flexibility to select and purchase the tools that best meet their needs, without having to wait for approvals or navigate bureaucratic purchasing processes, it can create challenges for the company. This can include reduced buying power, higher costs, lack of control over vendor relationships, and increased compliance and legal risks.

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Single-Tenancy Environment

What is a single-tenancy environment in cloud computing?


A single-tenancy environment, also known as dedicated hosting or a dedicated instance, refers to a situation where each user or tenant has their own dedicated infrastructure and resources, including servers, storage and network components. These resources aren’t shared with any other users, maximizing performance and control.

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