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Amazon ElastiCache
User Guide (API Version 2015-02-02)

Understanding Utilization Levels

There are three levels of node reservations – Heavy Utilization, Medium Utilization, and Light Utilization. Nodes can be reserved at any utilization level for either 1 or 3 years. The node type, utilization level, and reservation term will impact your total costs. You should verify the savings that reserved nodes can provide your business by comparing various models before you purchase reserved nodes.

Nodes purchased at one utilization level or term cannot be converted to a different utilization level or term.

Utilization Levels

Heavy Utilization reserved nodes enable workloads that have a consistent baseline of capacity or run steady-state workloads. Heavy Utilization reserved nodes require a high up-front commitment, but if you plan to run more than 79 percent of the reserved node term you can earn the largest savings (up to 70 percent off of the On-Demand price). With Heavy Utilization reserved nodes you pay a one-time fee, followed by a lower hourly fee for the duration of the term regardless of whether or not your node is running.

Medium Utilization reserved nodes are the best option if you plan to leverage your reserved nodes a substantial amount of the time, but you want either a lower one-time fee or the flexibility to stop paying for your node when you shut it off. Medium Utilization reserved nodes are a more cost-effective option when you plan to run more than 40 percent of the reserved nodes term. This option can save you up to 64 percent off of the On-Demand price. With Medium Utilization reserved nodes, you pay a slightly higher one-time fee than with Light Utilization reserved nodes, and you receive lower hourly usage rates when you run a node.

Light Utilization reserved nodes are ideal for periodic workloads that run only a couple of hours a day or a few days per week. Using Light Utilization reserved nodes, you pay a one-time fee followed by a discounted hourly usage fee when your node is running. You can start saving when your node is running more than 17 percent of the reserved node term, and you can save up to 56 percent off of the On-Demand rates over the entire term of your reserved node.

Reserved Cache Node Offerings

Offering Up-Front Cost Usage Fee Advantage

Heavy Utilization

Highest

Lowest hourly fee. Applied to the whole term whether or not you're using the reserved node.

Lowest overall cost if you plan to run your reserved nodes more than 79 percent of a three-year term.

Medium Utilization

Medium

Hourly usage fee charged for each hour the node is running. No hourly charge when the node is not running.

Suitable for elastic workloads or when you expect moderate usage, more than 40 percent of a three-year term.

Light Utilization

Lowest

Hourly usage fee charged for each hour the node is running. No hourly charge when the node is not running. Highest hourly fees of all the offering types, but fees apply only when the reserved node is running.

Highest overall cost if you plan to run all of the time; however, lowest overall cost if you anticipate you will use your reserved node infrequently, more than about 15 percent of a three-year term.

On-Demand Use (No reserved nodes)

None

Highest hourly fee. Applied whenever the node is running.

Highest hourly cost.

For more information, see Amazon ElastiCache Pricing.