Committed use discounts

Committed use discounts (CUDs) provide deeply discounted prices in exchange for your commitment to continuously spend a certain amount on Bigtable compute resources — nodes — for one year or three years.

CUDs are ideal when your spending on Bigtable nodes involves a predictable minimum that you can commit to for at least a year.

Bigtable CUD pricing

Bigtable offers two levels of discounts, depending on the commitment period:

  • A one-year commitment gives you a 20% discount from the on-demand rate, which is the standard, published rate.

  • A three-year commitment gives you a 40% discount from the on-demand rate.

When you purchase a commitment, you choose a one-year or three-year period. You also specify a commitment amount, which is your expected Bigtable expenditure on nodes per hour over that period. This commitment amount, after the application of your discount, becomes your commitment fee. You then receive the CUD, and you are billed for the commitment fee on a monthly basis for the duration of the CUD period.

The discount applies to all eligible node usage in Bigtable projects associated with the Cloud Billing account used to purchase the commitment, regardless of instance or region.

Any expenditure beyond the commitment is billed at the on-demand rate. As your Bigtable usage grows, you can purchase additional commitments to receive discounts on increased expenditures that are not covered by previous commitments.

If the on-demand prices for Bigtable nodes change after you purchase a commitment, your commitment fee does not change and you still receive the same discount percentage on applicable usage.

Eligible resources

Bigtable CUDs automatically apply to your spending on Bigtable compute capacity as measured in nodes across projects.

Bigtable CUDs do not apply to your spending on Bigtable storage, backup storage, or network data transfer.

Purchasing a commitment

Before you purchase a commitment, read the Service Specific Terms regarding Committed Units.

After you purchase a commitment, the discount goes into effect within the next hour and is automatically applied to subsequent eligible usage.

Make sure that the size and duration of your commitment aligns with both your historical and your expected minimum expenditure on Bigtable nodes.

To purchase or manage CUDs for a Cloud Billing account, follow the instructions at Purchasing spend-based commitments.

An example Bigtable CUD scenario

Ideally, your commitment represents at least your expected minimum hourly expenditure on Bigtable nodes across your projects over the next one or three years.

As an example, say that you have a Bigtable instance that has two clusters in different regions: us-central1 (Iowa) and us-west2 (Los Angeles). The cluster in us-central1 has 10 nodes and the cluster in us-west2 has 20 nodes.

From the pricing page, you can calculate the approximate hourly commitment cost:

  • Expenditure in us-central1: 10 nodes * $0.65 per node per hour = $6.50 per hour
  • Expenditure in us-west2: 20 nodes * $0.78 per node per hour = $15.60 per hour
  • Total expenditure across all regions: $6.50 + $15.60 = $22.10 per hour

If you expect to spend that minimum of $22.10 per hour continuously for the next year or more, then you can make a commitment for that amount. In other words, when purchasing the commitment, you enter "$22.10" as the hourly on-demand commitment amount.

On the other hand, if you expect to scale down your clusters sometimes, you can make a commitment for a lower amount. Any expenditure above the commitment amount is charged at the on-demand rate.

Continuing this example, assume that you decide on a commitment of $22.10 per hour. As your next step, you choose the length of the commitment period.

As a basis for comparison, calculate the on-demand cost of Bigtable node usage at the chosen commitment rate, without the application of any commitment discounts:

  • Monthly cost based on on-demand pricing: $22.10 per hour * 730 hours = $16,133 per month.

From here, you can calculate the monthly costs and savings that you would see under a 1-year commitment with a 20% discount compared to a year of paying the full rates:

  • Monthly cost of a 1-year, $22.10/hour commitment: ($22.10 per hour - 20% discount) * 730 hours = $12,906.40 per month
  • Total savings per month: $16,133 - $12,906.40 = $3,226.60
  • Total savings with a 1-year, $22.10/hour commitment: $3,226.60 per month * 12 months = $38,719.20

You can apply similar math to calculating the costs and savings of a 3-year CUD, a 40% discount compared to the on-demand rates:

  • Monthly cost of a 3-year, $22.10/hour commitment: ($22.10 per hour - 40% discount) * 730 hours = $9,679.80 per month
  • Total savings per month: $16,133 - $9,679.80 = $6,453.20
  • Total savings with a 3-year, $22.10/hour CUD: $6,453.20 per month * 36 months = $232,315.20

A commitment that covers your expected minimum Bigtable usage over the years to come can lead to significant savings.

Recommendations for choosing a commitment amount

While considering Bigtable CUDs and the amount that you want to commit to, keep in mind the following:

  • Regions: Bigtable CUDs apply to all nodes in a project, regardless of which region they are in. If you have Bigtable instances with clusters in multiple regions, calculate the expenditure across all the regions that your projects use before deciding whether to purchase a commitment.

  • Projects: Determine the consistent baseline expenditure per project while calculating total commitment. Consider that production loads usually run 100% of the time, while development or staging environments might often run intermittently.

  • Clusters: If you configure your Bigtable clusters to use a steady number of nodes around the clock, consider purchasing a commitment that covers all node usage. On the other hand, if you frequently scale your clusters up or down, either manually or through autoscaling, consider purchasing commitments only for your baseline predictable usage.

    If you have clusters that you run only for bursts or brief durations, exclude them from your calculations.

Your commitment fee applies to every hour during the term of the commitment, regardless of actual usage. Choose your commitment amount carefully, based on both your historical Bigtable usage and your future expectations. As long as your use of Bigtable nodes stays above your committed expenditure level, you receive the maximum possible discount for the length of the commitment.

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