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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 portion of the disk space is not available to host databases. Take this into account when selecting a configuration lineup.

You can monitor disk occupancy using disk occupancy notifications and metrics. For more information about metrics, see the Monitoring clusters, nodes, and databases MySQL semi-sync guide.

When the 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 a complete lockout or cluster corruption due to a lack of free space. To make the cluster read-write, scale 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.