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Using disk space in a MySQL semi-sync cluster

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In Managed Databases, part of the disk space is reserved for service needs:

  • for the file system — 4% of the disk volume;
  • for the operating system, service components, and logs — 8 GB.

The reserved portion of disk space is not available for hosting databases. Consider this when choosing a configuration lineup.

You can monitor the disk occupancy level using disk occupancy notifications and metrics. Learn more about metrics in the Monitoring clusters, nodes, and databases MySQL semi-sync guide.

When a cluster disk is 95% full or more, the cluster will enter the DISK_FULL status and will be read-only. This is necessary to prevent complete cluster lockout or corruption due to lack of free space. To restore read-write access to the cluster, resize the cluster and select a configuration with a larger disk size than the previous one.

Disk occupancy notifications

Disk occupancy notifications are sent to the email address of the Account Owner and users who are subscribed to the notification category "Services". Notifications are sent when the disk is 80% and 95% full.