mysqldump: errno: 28 No space left on device

OS

All

Software

6.9.0.0 and higher

Error message

mysqldump: Couldn't execute 'SELECT TRIGGER_NAME FROM INFORMATION_SCHEMA.TRIGGERS WHERE EVENT_OBJECT_SCHEMA = DATABASE() AND EVENT_OBJECT_TABLE = 'XXX'': Disk full (/tmp/#sql_673_0.MAI); waiting for someone to free some space... (errno: 28 "No space left on device") (1021)
mysqldump: Couldn't execute 'SHOW TRIGGERS LIKE 'XXX\_bug\_file\_table'': Got error 28 from storage engine (1030)

Cause

At the moment the export of a database starts the uncompressed space required for the export is reserved.
When there is insufficient free space in the temporary directory for this, the above error will occur for that database.
The MySQL database works in the following manner:

1. The backup manager will request a copy of the databases using a SQL-Query via sqldump.
2. The MySQL server will 'freeze' the status of the databases, but will still function by storing all transactions into logfiles.
3. The database will be copied by the SQL server into the temporary folder.
4. When the copying of the databases is finished, the database becomes writable again and the transaction logs are processed.
5. The OBM will read out the database and compares it with a previous backup, and (if there are differences) will create a incremental of differential file.
6. The full database or the differences will be uploaded to the backup server.

This process will result in a disk-space usage of 1.5 times the size of the databases in the temporary folder during the backup. Therefore you should assign a folder which can contain at least 1.5x as much data as the size of the databases combined.

Solution

We recommend you to choose a temporary folder on a disk which is not used for windows or the SQL server, to prevent problems.

1. Stop all running SQL backup tasks.
2. Remove the content of the temporarily directory of the SQL set.
3. Choose a different folder on a disk which has at least the free space available to contain 1.5 times the size of the database(s)
   1. Open the software
   2. Go to the backupset settings (cog)
      
   3. Choose the SQL backupset
   4. Go to the 'Options' tab
      
   5. Select a different temporary folder
   6. Click 'OK'
   7. Save the settings / Close the software
4. Start a manual differential backup of the SQL set.