Google Cloud Platform
Compute Engine

Regions and Zones

Certain Compute Engine resources live in regions or zones. A zone is an independent entity in a specific geographical location where you can run your resources. For example, a zone named us-central1-a indicates a location in the central United States.

Resources like an instance and persistent disk always live in a zone, while resources like static external IP addresses live in regions. You choose which region or zone to create your resources in, giving you control over where your data is stored and used. For example, when creating an instance or disk, you are prompted to select a zone where that resource serves traffic. Choosing a zone is important for several reasons:

Handling failures
It is important to distribute your resources across multiple zones to plan for scheduled or unscheduled zone outages. Because each zone is an independent entity, zone failures do not affect other zones. If a zone becomes unavailable, you can transfer traffic to another zone, allowing your services to remain running in the face of failures. For more information about distributing your resources and designing a robust system, see Designing Robust Systems.
Decreased network latency
To decrease network latency, you might want to choose a zone that is close to your point of service. For example, if you mostly have customers on the East Coast of the US, then you might want to choose a zone that is close to that area, in order to decrease latency between your virtual machine instances and your customers.

Resources that are specific to a zone or a region can only be used by other resources in the same zone or region. For example, disks and instances are both zonal resources. To attach a disk to an instance, both resources must be in the same zone. Similarly, if you want to assign a static IP address to an instance, the instance must be in the same region as the static IP.

The following diagram provides some examples of how regions and zones relate to each other. Notice that each region is independent of other regions and each zone is isolated from other zones in the same region.

Zones diagram describing zones available in each region

Contents

Identifying regions and zones

Each region in Compute Engine contains a number of zones. Each zone name contains two parts that describe each zone in detail. The first part of the zone name is the region and the second part of the name describes the zone in the region:

  • Region

    Regions are collections of zones. Zones have high-bandwidth, low-latency network connections to other zones in the same region. In order to deploy fault-tolerant applications that have high availability, Google recommends deploying applications across multiple zones in a region. This helps protect against unexpected failures of components, up to and including a single zone.

    Choose a region that makes sense for your scenario. For example, if you only have customers in the US, or if you have specific needs that require your data to live in the US, it makes sense to store your resources in zones in the us-central1 region or zones in the us-east1 region.

  • Zone

    A zone is an isolated location within a region. The fully-qualified name for a zone is made up of <region>-<zone>. For example, the fully-qualified name for zone a in region us-central1 is us-central1-a.

    Depending on how widely you want to distribute your resources, you may choose to create instances across multiple zones in multiple regions.

Available regions & zones

The following is a list of available regions and zones.

Region Location Available zones Features
Eastern US Berkeley County, South Carolina us-east1-b
us-east1-c
us-east1-d
Central US Council Bluffs, Iowa us-central1-a
us-central1-b
us-central1-c
us-central1-f
Western Europe St. Ghislain, Belgium europe-west1-b
europe-west1-c
europe-west1-d
East Asia Changhua County, Taiwan asia-east1-a
asia-east1-b
asia-east1-c

Each zone supports Ivy Bridge, Sandy Bridge, or Haswell processors. When you create an instance in the zone, your instance will use the processor supported in that zone. For example, if you create an instance in the us-central1-a zone, your instance will use a Sandy Bridge processor.

To view a list of available zones, you can always run:

gcloud compute zones list

To view a list of available regions using gcloud compute, use the regions list command. The command lists all available regions and provides information such as quotas and the status of the region itself. For example:

gcloud compute regions list
NAME         CPUS          DISKS_GB     ADDRESSES RESERVED_ADDRESSES STATUS
asia-east1      0.00/24.00      0/10240      0/23      0/7           UP
europe-west1    0.00/24.00      0/10240      0/23      0/7           UP
us-central1     0.00/24.00      0/10240      0/23      0/7           UP

To get information about a single region, use the gcloud compute regions describe command:

gcloud compute regions describe us-central1
creationTimestamp: '2013-09-06T17:54:12.193-07:00'
description: us-central1
id: '5778272079688511892'
kind: compute#region
name: us-central1
quotas:
- limit: 24.0
  metric: CPUS
  usage: 5.0
- limit: 5120.0
  metric: DISKS_TOTAL_GB
  usage: 650.0
- limit: 7.0
  metric: STATIC_ADDRESSES
  usage: 4.0
- limit: 23.0
  metric: IN_USE_ADDRESSES
  usage: 5.0
- limit: 1024.0
  metric: SSD_TOTAL_GB
  usage: 0.0
selfLink: https://www.googleapis.com/compute/v1/projects/myproject/regions/us-central1
status: UP
zones:
- https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-a
- https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-b
- https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-f

Transparent maintenance

Google regularly maintains its infrastructure by patching systems with the latest software, performing routine tests and preventative maintenance, and generally ensuring that Google infrastructure is as fast and efficient as Google knows how to make it.

By default, all instances are configured so that these maintenance events are transparent to your applications and workloads. Google uses a combination of datacenter innovations, operational best practices, and live migration technology to move running virtual machine instances out of the way of maintenance that is being performed. Your instance continues to run within the same zone with no action on your part.

By default, all virtual machines are set to live migrate, but you can also set your virtual machines to terminate and reboot. The two options differ in the following ways:

  • Live migrate

    Compute Engine automatically migrates your running instance. The migration process will impact guest performance to some degree but your instance remains online throughout the migration process. The exact guest performance impact and duration depend on many factors, but it is expected most applications and workloads will not notice.

  • Terminate and reboot

    Compute Engine automatically signals your instance to shut down, waits a short time for it to shut down cleanly, and then restarts it away from the maintenance event.

For more information on how to set the options above for your instances, see Setting Instance Scheduling Options.

Zone deprecation

Compute Engine has made recent improvements in its virtualization technology that eliminate the need to decommision an existing zone for a ground-up infrastructure refresh (power, cooling, network fabric, servers, etc.). Infrastructure refreshes are rare and zones typically run for three to five years between refreshes. These refreshes should be transparent to customers.

If it ever becomes necessary to deprecate a zone, Compute Engine will notify users well in advance of when it will go offline so you have ample time to move your virtual machine instances and workloads.

Quotas

Certain resources, such as static IPs, images, firewall rules, and networks, have defined project-wide quota limits and per-region quota limits. When you create these resources, it counts towards your total project-wide quota or your per-region quota, if applicable. If any of the affected quota limits are exceeded, you won't be able to add more resources of the same type in that project or region.

To see a comprehensive list of quotas that apply to your project, visit the Quotas page in the Google Cloud Platform Console.

For example, if your global target pools quota is 50 and you create 25 target pools in example-region-1 and 25 target pools in example-region-2, you reach your project-wide quota and won't be able to create more target pools in any region within your project until you free up space. Similarly, if you have a per-region quota of 7 reserved IP addresses, you can only reserve up to 7 IP addresses in a single region. After you hit that limit, you will either need to reserve IP addresses in a new region or release some IP addresses.

Tips

When selecting zones, here are some things to keep in mind:

  • Communication within and across regions will incur different costs.

    Generally, communication within regions will always be cheaper and faster than communication across different regions.

  • Design important systems with redundancy across multiple zones.

    At some point in time, it is possible that your instances might experience an unexpected failure. To mitigate the effects of these possible events, you should duplicate important systems in multiple zones.

    For example, if you host virtual machine instances in zones europe-west1-b and europe-west1-c, if europe-west1-b fails unexpectedly, your instances in zone europe-west1-c will still be available. However, if you host all your instances in europe-west1-b, you will not be able to access any of your instances if europe-west1-b goes offline. For more tips on how to design systems for availability, see Designing Robust Systems.