This document describes the different reservation types that you can use to reserve capacity for Compute Engine instances. To learn more about the resources that you can use to create instances, see Compute Engine instances.
Reservations help ensure that you have the available resources to create instances with the same hardware (memory and vCPUs) and optional resources (GPUs, TPUs, or Local SSD disks) whenever you need them. Reservations offer the following benefits:
High assurance of capacity: you reserve resources to accommodate for future increases in demand, such as the following:
Growth
Planned or unplanned spikes in usage
Large migrations
Backup and disaster recovery
Exclusive access: reservations prevent others from using your reserved resources.
Inherited properties: reservations inherit the same properties as your chosen machine family.
After you reserve capacity, you can use it to create instances that match the reservation. You don't incur any additional charges when you create these instances. You only pay for resources that aren't part of the reservation, such as disks or IP addresses.
Limitations
All reservation types have the following limitations:
Reservations are zone-specific resources.
You can't use your reserved capacity to create the following Compute Engine resources:
Spot VMs or preemptible instances
Sole-tenant nodes
Choose a reservation type
The following diagram helps you choose the Compute Engine reservation type that best fits your workload's needs:
The questions in the preceding diagram are as follows:
Do you need capacity right away?
Yes: Go to question 2.
No: Go to question 3.
Do you need flexibility on how long to hold capacity?
Yes: See Use on-demand reservations.
No: Go to the next question.
Do you need to reserve TPUs?
Yes: See Use future reservations in calendar mode.
No: See Use future reservations.
Use on-demand reservations
With on-demand reservations, you can reserve capacity for compute instances and get it as soon as you reserve it. After you create an on-demand reservation, you can consume, modify, or delete it whenever you need to.
For more information, see About reservations.
Use future reservations
With future reservations, you can request to reserve capacity for a predefined period. After you create a reservation request, you must submit it to Google Cloud for review. Within five business days, Google Cloud reviews your request. If approved, Compute Engine creates on-demand reservations with your requested capacity at your chosen date and time. You can then consume the reservations by creating compute instances that use them. You modify or delete reservations only after your reservation period ends.
For more information, see About future reservation requests.
Use future reservations in calendar mode
You can use future reservations in calendar mode to reserve TPUs for a predefined period. To create this type of reservation, you first view when your chosen number and type of TPUs are available in a region. Then, you create a reservation request with the properties that you confirmed as available, and submit the request for review. Google Cloud reviews your request within a minute and, if it approves your request, Compute Engine does the following:
Compute Engine creates an on-demand reservation.
Compute Engine reserves your requested resources as close to each other as possible to minimize network latency.
At the start of your reservation period, you can then consume the reservation by creating TPU instances. Compute Engine deletes the reservation, and any instances that consume it, at the end of your specified reservation period.
For more information, see About future reservation requests in calendar mode.