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MySQL error 1030 with error 28 means the operating system refused a write because the target filesystem has no usable space left. Find the full filesystem first, then free or move space and address the operation that consumed it. Check both MySQL’s data directory and its temporary-file locations: changing tmpdir does not move the InnoDB temporary tablespace file ibtmp1.
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What “Got error 28 from storage engine” means
The complete message is commonly shown as ERROR 1030 (HY000): Got error 28 from storage engine. Error 1030 is MySQL’s wrapper; error 28 is the operating system error number for ENOSPC, “No space left on device.” InnoDB tried to create or extend a file and the operating system could not satisfy the write.
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The same condition can appear outside a SQL statement. For example, a dump can fail with errno: 28 No space left on device, and an application can report an error writing a file under /tmp. Those messages point to the same investigation: identify the full mount point, not just the database name.
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First response: stop making the full filesystem worse
- Record the failing operation and time. Note whether it was an index build,
ALTER TABLE,OPTIMIZE TABLE, import, backup, or an ordinary query. This helps identify temporary-space demand later. - Pause retries. Repeatedly rerunning a failed DDL statement can create more temporary files and fill the remaining blocks or inodes.
- Check free space and inodes before deleting anything. A filesystem can reject writes because it has no blocks or no inodes.
- Preserve the error log and active backup files. Do not remove a file that a running backup, replication process, or database operation still has open.
Find which filesystem is full
Run these checks on the database host, using an account that can inspect the relevant paths:
df -h
df -i
df -h /tmp
df -h /var/lib/mysqlReplace /var/lib/mysql with the actual MySQL data-directory path. The df -h output shows block usage; df -i shows inode usage. If the percentage is near 100 percent, note the mount point rather than assuming the data directory is responsible.
Ask MySQL which directories it is configured to use:
SHOW VARIABLES LIKE 'datadir';
SHOW VARIABLES LIKE 'tmpdir';
SHOW VARIABLES LIKE 'innodb_data_home_dir';
SELECT @@innodb_temp_data_file_path;Check every filesystem returned by those values. A separate mount for /tmp can be full while the data partition has room, or the reverse can be true.
Read the MySQL error log around the failure. The path in a “cannot write,” “unable to create temporary file,” or “error writing file” message often identifies the exact filesystem. If the log names only a relative file, resolve it against the data directory or the configured temporary directory.
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Identify what consumed the space
After locating the full mount, inspect its largest directories and files. On Linux, start with a depth-limited summary so the scan does not itself become expensive:
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sudo du -xhd1 /var/lib/mysql | sort -h
sudo du -xhd1 /tmp | sort -hUse the corresponding mount path from df; the examples above are not universal locations. Common consumers are:
| Consumer | Why it grows | What to check |
|---|---|---|
Temporary directory (tmpdir) |
Sorts, joins, online DDL, repairs, imports, and other operations spill to disk when memory is insufficient. | Large temporary files, permissions, and the filesystem containing the configured path. |
Global InnoDB temporary tablespace (ibtmp1) |
On-disk internal temporary tables extend the file. Dropping a temporary table makes space reusable inside the file but does not reduce its filesystem size. | The file’s size on disk and @@innodb_temp_data_file_path. |
| Data directory | Permanent table data, indexes, undo-related files, and other database files consume the partition. | Per-database directories and unexpectedly large table files. |
| Binary and relay logs | Logs accumulate when retention or replication cleanup does not remove older files. | Configured expiration, replication status, and whether a replica still needs each log. |
Old dumps in /tmp |
Backups or exports left behind after an interrupted job can occupy the temporary filesystem. | File ownership, modification time, and whether a process still has the file open. |
Do not delete database files from the data directory by hand. Permanent table, redo, undo, and system files require MySQL-aware procedures. Removing the wrong file can prevent startup or cause data loss.
Free space safely for an immediate recovery
Remove confirmed leftovers
Delete completed dumps, abandoned exports, and stale temporary files only after confirming that no process is using them. Check open handles before removal with your operating system’s file-process tools; a deleted-but-open file may not return space until the owning process closes it.
Keep enough free capacity for MySQL to finish recovery and for the operating system to write logs. Clearing only a few megabytes may allow one statement to start but leave the server vulnerable to another failure.
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Purge old binary or relay logs through the supported mechanism
Logs can be a major consumer, but retention is part of recovery and replication design. Verify that replicas have received the logs and that no point-in-time recovery policy requires them. Then use MySQL’s documented log-expiration or purge procedure rather than deleting log files with rm. If you cannot establish that a log is safe to remove, free space elsewhere first.
Reduce the immediate operation
A large sort, join, import, index build, or table rebuild can require temporary space comparable to the data being processed. Canceling a runaway statement may release temporary objects, although an already enlarged ibtmp1 file will remain physically large until a restart. Break a bulk change into smaller batches, schedule it when capacity is available, or perform it on a host with a larger temporary filesystem.
Understand tmpdir and ibtmp1 separately
These settings solve different storage problems:
| Setting or file | Role | How space is reclaimed | Does changing the other setting move it? |
|---|---|---|---|
tmpdir |
Directory for many server temporary files, including sorts, joins, and some DDL work. | Files are removed when operations finish; relocating the directory changes where new files are written. | No. Changing tmpdir does not relocate ibtmp1. |
ibtmp1 (global InnoDB temporary tablespace) |
Shared InnoDB tablespace for internal on-disk temporary tables. It starts at a little over 12 MB by default and auto-extends. | Released pages are reused internally. The file’s allocated size remains until the server is restarted and the temporary tablespace is recreated. | No. It is controlled by innodb_temp_data_file_path. |
In MySQL 5.7, compressed temporary tables use file-per-table temporary tablespaces in tmpdir, which is another reason to check both locations.
Move temporary files to a larger filesystem
Relocate tmpdir
Use a dedicated filesystem with sufficient headroom and appropriate ownership and permissions. Create the directory, make sure the MySQL service account can use it, and set the server’s tmpdir option in the applicable MySQL configuration file. The exact file location differs by distribution; inspect the active service configuration rather than editing an unused sample file.
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SHOW VARIABLES LIKE 'tmpdir';Changing tmpdir helps operations that use ordinary temporary files. It does not move the global InnoDB temporary tablespace.
Relocate or constrain the InnoDB temporary tablespace
Configure innodb_temp_data_file_path for the InnoDB temporary tablespace. A MySQL 5.7-style example is:
innodb_temp_data_file_path=ibtmp1:12M:autoextend:max:500MThe example sets an initial size of 12 MB, permits automatic extension, and caps the file at 500 MB. Choose a limit based on the largest legitimate workload; the number is not a universal recommendation. A cap prevents unlimited growth but introduces a hard failure mode: when the file reaches its maximum, statements needing more InnoDB temporary space fail with a “table is full” style error.
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SELECT @@innodb_temp_data_file_path;Some MySQL documentation examples show a separate path for ibtmp1. Treat those as configuration examples, not a guarantee that any arbitrary relative path is valid on your installation; confirm the rules for your exact MySQL version and operating system.
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Reclaim an oversized ibtmp1
When temporary objects are dropped, their pages become available for reuse, but the file itself does not shrink. To reclaim the filesystem space, perform a controlled MySQL restart. Before restarting:
- Confirm that replication, backups, and application failover procedures can tolerate the interruption.
- Resolve the underlying workload that caused the growth; otherwise the file can expand again immediately.
- Ensure the filesystem has enough free space for normal startup and recovery.
- Capture current values of
@@innodb_temp_data_file_path,datadir, andtmpdirso you can verify the post-restart configuration.
After startup, check the file size on disk and monitor the next heavy operation. A restart is a reclamation mechanism, not a permanent capacity plan.
Find the query that keeps rebuilding temporary space
If ibtmp1 or tmpdir fills repeatedly, look for statements that spill large intermediate results:
- Large joins or sorts without selective indexes.
- Aggregations or
ORDER BY/GROUP BYoperations that cannot remain in memory. - Online index creation and table-altering operations.
REPAIR TABLE,OPTIMIZE TABLE, and bulkLOAD DATA INFILEjobs.- Imports or reports that run concurrently and multiply temporary-space demand.
Use the slow-query log, performance monitoring, and the process list to correlate the growth with statements. Improve indexes and predicates, process data in batches, reduce unnecessary concurrency, or schedule the operation on a larger volume. Raising memory limits can reduce disk spills in some workloads, but it does not replace filesystem capacity and can create operating-system memory pressure.
What to do if MySQL will not start after the disk filled
- Free space on the filesystem identified by the error log, starting with confirmed non-database leftovers.
- Check both blocks and inodes with
df -handdf -i. - Read the startup error log for the exact file or directory that cannot be created or extended.
- Verify ownership and permissions on the data directory,
tmpdir, and any configured temporary-tablespace path. - Start MySQL using the normal service manager and monitor the log until recovery completes.
Do not initialize a new data directory, remove InnoDB system files, or delete redo and undo files as a “cleanup” step. Those actions can destroy the only usable copy of the database.
Version and configuration considerations
The temporary-tablespace behavior described here is documented for MySQL 5.7 and 8.0, but option syntax, dynamic-variable support, and path rules can differ by release and packaging. Check the manual for the exact server version before applying a configuration change. In particular, verify whether your release documents the same maximum-size behavior for innodb_temp_data_file_path; do not assume a 5.7 example has identical semantics everywhere.
An official example that points ibtmp1 to another path may be illustrative or read-only documentation. Validate it in a staging environment and confirm the resulting file location after restart.
Prevent another error 28
- Alert on filesystem usage before it reaches the point where MySQL cannot write; keeping temporary volumes comfortably below capacity leaves room for sudden operations.
- Monitor both block and inode utilization.
- Track the size of
ibtmp1, the configuredtmpdir, database files, and binary or relay logs separately. - Set log-retention policies that account for replication and point-in-time recovery.
- Give scheduled dumps and exports a destination with known capacity instead of relying on an unmonitored
/tmp. - Test large DDL, imports, and reports in a non-production environment and measure their peak temporary-space use.
- Document restart procedures and the maintenance impact of changing
innodb_temp_data_file_path. - Review queries that repeatedly create large temporary tables rather than relying only on a larger disk.
Quick decision guide
| Observation | Most appropriate next action | Trade-off |
|---|---|---|
/tmp is full of completed dumps or stale files |
Remove confirmed leftovers and redirect future jobs. | Fast and reversible, but recurrence remains if the job continues to write there. |
| The data partition is full from logs | Validate retention and replication, then purge logs through MySQL’s supported process. | Reclaims space without changing table data, but careless purging can remove recovery or replica requirements. |
ibtmp1 is very large but the workload has ended |
Schedule a restart to recreate the global temporary tablespace. | Requires downtime and does not prevent future growth. |
| Temporary operations routinely exceed the current volume | Move tmpdir, move or size ibtmp1 appropriately, or enlarge the filesystem. |
Provides durable capacity but requires configuration, testing, and often a restart. |
| A single query causes repeated growth | Tune the query, add suitable indexes, batch the work, or reduce concurrency. | Addresses the cause, but may require application or schema changes. |
| You cannot identify a safe file to delete | Stop cleanup and obtain an administrator familiar with the server’s backup and replication state. | Slower than deletion, but avoids irreversible data loss. |
Bottom line
Error 28 is the operating system saying that the filesystem needed by MySQL has no space—or no available inodes. Use df, MySQL’s path variables, and the error log to locate that filesystem before taking action. Free safe leftovers or logs for immediate relief, distinguish tmpdir from the InnoDB temporary tablespace, and use a planned restart or configuration change to deal with an oversized ibtmp1. Then fix the workload or retention policy that caused the growth so the error does not return.
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