Error
Error Code:
3
MySQL Error 3: File Write Failure
Description
This error indicates that MySQL was unable to write data to a file on the operating system. This typically occurs when the database attempts to create, update, or log information but encounters an underlying issue preventing the write operation.
Error Message
Error writing file '%s' (OS errno %d - %s)
Known Causes
3 known causesInsufficient File Permissions
The MySQL user lacks the necessary write permissions for the target directory or file, preventing the database from performing write operations.
Disk Space Exhaustion
The storage volume where MySQL attempts to write data has run out of available disk space, making further write operations impossible.
File System Issues
The underlying file system is in a read-only state, corrupted, or experiencing other issues that prevent data from being written.
Solutions
4 solutions available1. Check Disk Space and Permissions easy
Ensure the MySQL data directory and temporary directories have sufficient space and correct write permissions.
1
Check available disk space on the partition where MySQL data and temporary files are stored. The error message 'OS errno %d - %s' often indicates disk full or permission issues.
df -h2
Identify the MySQL data directory. This is usually defined in your `my.cnf` or `my.ini` file under the `datadir` variable.
SHOW VARIABLES LIKE 'datadir';3
Identify the MySQL temporary directory. This is usually defined by `tmpdir` in your `my.cnf` or `my.ini` file. If not explicitly set, it defaults to the system's temporary directory.
SHOW VARIABLES LIKE 'tmpdir';4
Verify that the MySQL user (typically `mysql`) has write permissions to these directories. If not, grant them.
sudo chown -R mysql:mysql /path/to/mysql/datadir
sudo chmod -R 755 /path/to/mysql/datadir
sudo chown -R mysql:mysql /path/to/mysql/tmpdir
sudo chmod -R 755 /path/to/mysql/tmpdir5
Restart the MySQL service after making permission changes.
sudo systemctl restart mysql2. Examine MySQL Error Log for Specifics medium
Detailed examination of the MySQL error log can pinpoint the exact file and OS error causing the write failure.
1
Locate your MySQL error log file. Its location is specified by the `log_error` variable in your `my.cnf` or `my.ini` file.
SHOW VARIABLES LIKE 'log_error';2
Open the error log file and search for recent entries related to 'File Write Failure' or the specific filename mentioned in the error message. Pay close attention to the OS error number (e.g., EACCES for permission denied, ENOSPC for no space left).
tail -f /var/log/mysql/error.log3
Based on the OS error code, take appropriate action. For example, if it's `ENOSPC`, free up disk space. If it's `EACCES`, check and correct file/directory permissions.
N/A3. Check for Antivirus or Security Software Interference medium
Third-party security software might be blocking MySQL's write operations.
1
Temporarily disable any antivirus, endpoint protection, or other security software that might be monitoring or restricting file access.
N/A (Consult your security software's documentation for disabling procedures)2
Attempt to perform the operation that previously failed. If it succeeds, the security software was the cause.
N/A3
If the security software is the culprit, configure it to exclude the MySQL data directory, log files, and temporary directories from real-time scanning or blocking.
N/A (Consult your security software's documentation for exclusion/whitelist configuration)4. Investigate Filesystem Issues or Corruption advanced
Underlying filesystem problems can lead to write failures.
1
Unmount the filesystem where MySQL data is stored.
sudo umount /path/to/mysql/datadir_partition2
Run a filesystem check (e.g., `fsck` for Linux). This process may require downtime for the affected partition.
sudo fsck /dev/sdXn (replace /dev/sdXn with your partition)3
If filesystem corruption is found and repaired, remount the partition.
sudo mount /path/to/mysql/datadir_partition4
Restart MySQL and check if the issue persists.
sudo systemctl restart mysql