Question

One or more connectors are failing with the error OS errno 28 - No space left on device being displayed in the Fivetran dashboard, even though there is seemingly plenty of disk space.

Environment

Destination: MySQL

Answer

This is a tricky issue for which there are several potential resolutions, one or more of which can be utilized to try to resolve the issue:

• Increase the instance size that the database is running on (particularly its RAM)
• Increase the InnoDB buffer pool size
• Delete old or unused data to clear enough disk space
• Add a significant amount of disk space as an extra 'overflow'

However, the best recommendation is to migrate to a much more robust and scalable warehouse solution such as Snowflake, BigQuery, or Redshift.

Cause

This can occur when Fivetran run any SQL query (such as a JOIN operation) against the warehouse. If the RAM available to the instance that runs the database or the InnoDB buffer pool size is not sufficient for the query at that time, a temporary table is created on disk. This table can be quite large in some cases, even though only small amounts of data are being transferred.

Because of this limitation with MySQL as a destination, Fivetran throws a warning when you try to set this as  destination: