MySQL 1166: Error writing to file.

What is MySQL 1166: Error writing to file.

When encountering the error 1166: Error writing to file in MySQL, perform the following immediate actions:

Check Disk Space: Ensure the server has enough disk space. Run the command:

df -h This checks the available disk space on all mounted filesystems. If the disk is full, freeing up space or increasing disk size is required.

Check Permissions: Verify that the MySQL user has write permissions to the directory and files it's trying to access. Run the command:

ls -l /path/to/mysql/data/directory Replace `/path/to/mysql/data/directory` with the actual path. Ensure the files and directories have the correct owner (usually 'mysql' or 'mysqld').

Review MySQL Error Log: The MySQL error log can provide specific details about why the write failed. Check the log with:

tail -f /var/log/mysql/error.log Adjust the path `/var/log/mysql/error.log` based on your MySQL configuration. Look for any errors related to disk space, permissions, or other issues concurrent with the error 1166.

Check for Read-only Filesystem: Ensure the filesystem where MySQL writes its data isn't mounted as read-only. Run:

mount | grep /path/to/mysql/data Replace `/path/to/mysql/data` with the actual data directory. Look for `(ro,` in the output, indicating a read-only mount.

Check InnoDB Status: If the table uses InnoDB, there might be information related to the error in the InnoDB engine status. Run:

SHOW ENGINE INNODB STATUS; Look in the 'LATEST FOREIGN KEY ERROR' and 'LATEST DETECTED DEADLOCK' sections for any relevant errors.

Repair Table: If the issue is with a specific table and it's not InnoDB, you can attempt to repair it with:

REPAIR TABLE tablename; Replace `tablename` with the name of the affected table.Perform these actions sequentially to diagnose and potentially resolve the "Error 1166: Error writing to file" in MySQL.