sqlio.exe

SQL I/O Benchmark Utility

Command-Line ToolSafeDisk Benchmark

CPU Usage

1-10%

Memory

5-50 MB

Location

C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\Binn

Publisher

Microsoft Corporation

Quick Answer

sqlio.exe is a legitimate benchmarking tool. It runs configurable I/O workloads to measure disk performance for SQL Server environments.

Is it a Virus?

✔ NO - Safe

Typically located in a Microsoft SQL Server tools directory

Warning

Low-level benchmark tool

Executes controlled I/O patterns; ensure proper test scope

Can I Disable?

✔ YES

Terminate the command window or stop the test when finished

What is sqlio.exe?

sqlio.exe is a command-line utility used to generate controlled I/O workloads on a disk or file to simulate SQL Server I/O patterns. It helps DBAs evaluate disk performance under various block sizes and access types.

It creates configurable read/write operations per an ini-style configuration, enabling precise control of IOPS, queue depth, offsets, and test duration for realistic benchmarking.

Quick Fact: SQLIO is a widely used tool to stress test storage before SQL Server deployment to verify hardware readiness.

Types of SQLIO Operations

Sequential Write: Writes data contiguously to measure sustained throughput
Random Read/Write: Simulates random I/O to assess IOPS under non-sequential access
Buffered vs Unbuffered IO: Configures cache behavior to reflect real workloads
Latency Measurements: Captures per-operation latency during tests

Is sqlio.exe Safe?

Yes, sqlio.exe is safe when obtained from legitimate Microsoft SQL Server tooling or official SQLIO distributions and used as intended for benchmarking.

Is sqlio.exe a Virus or Malware?

The legitimate sqlio.exe is not a virus. Malware can masquerade as it; verify path and signatures.

How to Tell if sqlio.exe is Legitimate or Malware

File Location: Must be in a Microsoft SQL Server tools directory, e.g. C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\Binn\sqlio.exe or C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\Binn\sqlio.exe. Any other location is suspicious.
Digital Signature: Right-click sqlio.exe in Explorer -> Properties -> Digital Signatures. Should show a valid Microsoft signature, e.g., 'Microsoft Corporation'.
Hash Verification: Compare file hash with official distribution SHA256 from Microsoft. Use Get-FileHash -Algorithm SHA256 on the path.
Resource Behavior: Legitimate tests run with explicit workload; idle background execution is unlikely.

Red Flags: If sqlio.exe is found in Temp, AppData, or System32 without a legitimate SQL Server tooling installation, or if it runs without a test configuration, treat as suspicious and scan.

Why Is sqlio.exe Running on My PC?

sqlio.exe runs when you execute a SQL I/O benchmark, or when a script or monitoring tool invokes a storage test using predefined configurations.

Reasons it's running:

Active Benchmark Session: A user or automation script is actively performing a disk I/O benchmark against a chosen file or drive.
Scheduled Tests: Automated maintenance or performance tests trigger sqlio.exe at scheduled times.
Test Files Accessed: The tool reads/writes to the target test file path to simulate workloads.
Background Monitoring: Some performance monitoring suites invoke sqlio during validation of IO subsystem.
Incorrect/Failed Cleanup: Residual sqlio.exe processes may linger if prior tests did not terminate properly.

Can I Disable or Remove sqlio.exe?

Yes, you can disable or remove sqlio.exe. Only disable it if you no longer perform disk benchmarks, and remove it if it came with an old SQL IO toolkit you no longer use.

How to Stop sqlio.exe

End Test Process: If running in a command prompt, press Ctrl+C to stop the test
End via Task Manager: Open Task Manager, locate sqlio.exe and End Task
Close Scripts: If invoked by a script, terminate the script or stop the job
Disable Startup: If sqlio.exe starts from a task, disable the task in Task Scheduler or startup items
Uninstall Toolkit: If part of an SQL Server tools package, uninstall from Programs and Features or remove the toolkit

How to Uninstall SQL IO Toolkit

✔ Windows Settings -> Apps -> Apps & Features -> select SQL IO Toolkit -> Uninstall
✔ Control Panel -> Programs -> Uninstall a program -> select SQL IO Toolkit -> Uninstall
✔ If sqlio.exe is part of SQL Server, consider leaving the server components or upgrading to supported tools

Common Problems: Disk Benchmark Issues

If sqlio.exe reports errors or runs slowly, follow these typical troubleshooting steps for I/O benchmarks.

Common Causes & Solutions

Insufficient permissions: Run as Administrator or grant read/write access to test directory
Wrong test file path: Ensure the file path exists and has necessary permissions
Incorrect cache settings: Adjust buffered vs unbuffered I/O and cache policy in the ini file
Drive linkage or storage tier issues: Test different volumes or external drives to isolate bottlenecks
Resource contention: Close other heavy applications; limit concurrency in test config
Unsupported hardware: Some older hardware may not support the selected I/O patterns; adjust block sizes

Quick Fixes:
1. Run sqlio.exe with elevated privileges
2. Ensure test directory is on fast storage
3. Check available free space
4. Reduce number of concurrent threads
5. Review test configuration for correctness

Frequently Asked Questions

Is sqlio.exe safe to run on my system?

Yes when obtained from official Microsoft SQL Server tooling; ensure it matches the expected path in your SQL Server installation.

What does sqlio.exe do exactly?

sqlio.exe generates configurable I/O workloads to measure throughput, latency and IOPS on disks used by SQL Server.

How do I run sqlio.exe?

Open a command prompt with admin rights, navigate to the sqlio.exe location, and run with an ini file describing patterns or use with default parameters.

Can sqlio.exe harm my storage?

In typical use it performs read/write operations; improper configurations could impact performance temporarily, but it should not corrupt data if used on proper test files.

Where should sqlio.exe be located?

Commonly under <code>C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\Binn\</code> or the SQL Server Tools directory; verify with your instance path.

How can I interpret sqlio.exe results?

Results show IOPS, throughput, latency per operation, and workload mix; compare against baseline to assess storage performance.