The check command operates by
running a CRC check on the schema or table specified, creating a
temporary table containing the check data and values during the process.
The data collected during this process is then written to a consistency
table within the replication configuration schema and is used to verify
the table data consistency on the Primary and the Replica.
Because the check operation is creating a temporary table containing a CRC of each row within the specified schema or specific table, the size of the temporary table created can be quite large as it consists of CRC and row count information for each row of each table (within the specified row limits). The configured directory used by MySQL for temporary table creation will need a suitable amount of space to hold the temporary data.