bdflush - Linux

Overview

bdflush is a Linux command that forces the kernel to flush all dirty block device buffers (cache) to their corresponding persistent storage devices. Dirty buffers are memory blocks holding modified file data that have not yet been written to permanent storage.

Syntax

bdflush [options]

Options/Flags

-a: Flush all dirty buffers.
-b: Flush only the dirty buffers for block devices.
-d: Flush only the dirty buffers for directories.
-e: Flush only the dirty buffers for files with certain extensions (requires -f).
-f [list of extensions]: Specify the file extensions to consider for -e.
-i: Flush only the dirty buffers for files with certain inode numbers (requires -n).
-n [list of inode numbers]: Specify the inode numbers to consider for -i.
--version: Display version information.
--help: Display help information.

Examples

Flush all dirty buffers:
```
bdflush -a
```
Flush only dirty buffers for block devices:
```
bdflush -b
```
Flush only dirty buffers for files with .txt extension:
```
bdflush -e -f txt
```

Common Issues

Slow performance: If bdflush takes a long time to complete, it could indicate a problem with the underlying storage device. Check disk health and try again.

Integration

Combine with sync: Run sync before bdflush to ensure all pending file system metadata is written to storage before flushing dirty buffers.

Related Commands

sync: Flushes pending file system metadata.
fuser: Lists processes using a specific file.