Committed Use Discounts (CUDs) allow any customer to receive a substantial discount by committing to use a minimum quantity of concurrent GCE resources and reservations for 1 year or 3 years. Reservations allow you to reserve certain GCE resources (vCPUs, memory, GPUs, PD and/or Local SSD) in a specific Zone for later consumption without the hassle of running and monitoring VMs to hold the desired capacity.
Committed use discounts are ideal for workloads with predictable resource needs. When you purchase a committed use contract, you purchase compute resources (vCPUs, memory, GPUs, and local SSDs) at a discounted price in return for committing to paying for those resources for 1 year or 3 years. The discount is up to 57% for most resources like machine types or GPUs. The discount is up to 70% for memory-optimized machine types.[1].
By default, committed use discounts apply at the project level, but you can enable discount sharing from your billing account to share discounts across multiple projects.
Note:
1- After you create a commitment, you can't cancel it. You must pay the agreed upon monthly amount for the duration of the commitment
2- After you purchase a commitment, you can't change it. If you need to modify a commitment, purchase a new commitment with a new expiration date for the incremental amount.
After purchasing, you are billed monthly for the resources you purchased for the duration of the term you selected, whether or not you use the services. If you have a predictable workload, you can use discounts to help you cut costs on resources that you need.
Committed use discounts work on most Compute Engine machine types, including predefined and custom machine types, however, f1-micro and g1-small shared-core machines are excluded. Committed use discounts are simple and flexible, and require no upfront costs. Discounts apply to the aggregate number of vCPUs, memory, GPUs and local SSDs within a region, so they are not affected by changes to your instance's machine setup.
For your particular use cases please read the section “ How committed use discounts work” [1] and you will know in detail.
For example, if you purchase a commitment for 8 cores, and you run 24 cores during the month, you will receive committed use discounts for 8 cores. The other 16 cores will be billed at standard, non-committed use rates. Keep in mind that after you purchase a set amount of commitments, you're billed for those commitments monthly, even if you don't use them. For example, if you purchase commitments for 8 cores, you're billed the committed use rates for those 8 cores for the whole month, even if you might have only run these cores for a part of the month. It is to your advantage to purchase commitments only in increments you know you will use.
You can scale up but will be charged at standard billing for the differences in the resource .
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