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Using disk space in a MySQL semi-sync cluster

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 part of the disk space is not available for hosting databases. Keep this in mind when choosing a configuration line.

You can track disk usage using disk full notifications and metrics. Learn more about metrics in the instructions on Cluster, node, and database monitoring MySQL semi-sync.

When the cluster disk is 95% or more full, the cluster will enter the DISK_FULL status and become read-only. This is necessary to prevent complete locking or damage to the cluster due to a lack of free space. For the cluster to work in read-and-write mode, scale the cluster and select a configuration with a larger disk size than in the previous configuration.

Disk occupancy notifications

Disk full notifications are sent to the email addresses of the Account Owner and users subscribed to the notification category “Products and services”. Notifications are sent when the disk is 80% and 95% full.