This page describes operations that impact availability in Cloud SQL.

Cloud SQL helps you maximize the uptime of your database without anychanges to your application. With a 99.99% uptimeSLA andnear-zero downtime for several planned operations,Cloud SQL Enterprise Plus edition offers greater resilience and business continuity for yourapplications.

Maximizing uptime means reducing the downtime for your database.Downtime is typically caused by both unplanned events and planned operations.

Unplanned events and zonal outage

For applications that require high availability, we recommend configuringthe instance for regional availability, also referred to as thehigh availability (HA) configuration in Cloud SQL.For more information about configuring high availability in Cloud SQL, seeAbout high availability (HA).

For instances configured with regional availability, if the instanceencounters a failure, then Cloud SQL automatically brings up theinstance in the secondary zone with the same IP address andno data loss so that applications can resume operations on the database.This protects against unplanned events such as the failure of a single VMhost, or the failure of one or more infrastructure components that causesthe outage of an entire zone.

Cloud SQL high availability is available for both Cloud SQL Enterprise Plus edition andCloud SQL Enterprise edition.

If you don't configure regional availability for an instance, then the instanceis configured for zonal availability, also referred to as astandalone instance.

Cloud SQL recovers standalone instances (instances configured with zonal availability)from VM host failures automatically.However, Cloud SQL doesn't recover standalone instances from a zonaloutage automatically. To re-establish a standalone instance in a healthy zone,you must restore any standalone instances manually.You can recover a standalone instance from a zonal outage manually byperforming either point-in-time-recovery or by promoting a read replica tobecome the standalone instance. For more information, seeRecovery options for standalone instances.

Planned operations with near-zero downtime

For planned operations such as maintenance or some instance reconfigurations,Cloud SQL Enterprise Plus edition offers near-zero downtime forprimary instances with no application changes or proxy requirements.

The following planned operations benefit from the near-zero downtimeon a Cloud SQL Enterprise Plus edition primary instance. These downtimes are applicable toboth standalone (zonal) and high availability (regional) instances.

• Maintenance, which includes thefollowing operations with sub-second downtime:

  • Automatic maintenance that Cloud SQL performs every quarter
  • Self-service maintenance that you can initiate at any time
  • Maintenance simulation that you can initiate to test thesub-second downtime behavior

• Minor version upgrade
  • Perform a minor version upgrade on a MySQL 8.0 instance with sub-seconddowntime

• Instance scaling

  • Scale-up: Increase the compute size (vCPU, memory) of yourCloud SQL instance as frequently as needed

  • Scale-down: Reduce the compute size (vCPU, memory) of yourCloud SQL instance infrequently

    Note: If you scale down your instance more than once during a three-hour period, then only the first scale down event benefits from near-zero downtime. Subsequent scale down events experience regular downtime.

• Data cache

  • Enable or disable data cache as frequently as needed

• Edition upgrade

  • Perform an in-place upgrade to Cloud SQL Enterprise Plus edition

What's next

• Learnabout high availability (HA)

• Enable or disable high availability (HA)

• Readabout disaster recovery (DR)

• View all theGoogle Cloud services available in locations worldwide.