hdparm command in Linux with Examples

Last Updated : 27 Sep, 2024

"hdparm" (i.e., hard disk parameter) is one of the command line programs for Linux that is used to handle disk devices and hard disks. With the help of this command, you can get statistics about the hard disk, alter writing intervals, acoustic management, and DMA settings. It can also set parameters related to drive caches, sleep mode, power management, acoustic management, and DMA settings.

Syntax

 hdparm [options] [device]

where,

options: Specifies the parameter you want to get or set.
device: Specifies the disk device you want to apply the command to, typically something like '/dev/sda' or '/dev/vdb'.

Note: When no flags are specified, '-acdgkmnru' is presumed.

Commonly Used hdparm Options

Option	Description
`-a`	Get/set enumeration of a section of file system read-ahead, improving performance for large file reads.
`-A`	Enable/disable the IDE drive’s read-ahead feature, which is generally enabled by default.
`-b`	Get/set bus state: (0 = Off, 1 = On, 2 = tristate).
`-B`	Set Advanced Power Management (APM) settings. Lower values increase power-saving, while higher values improve performance. Set to 255 to disable APM.
`-c`	Query/enable 32-bit I/O support for (E)IDE drives, which refers to input transmission over PCI or VLB bus.
`-C`	Inspect the current power mode of the IDE drive. Useful with power management options like `-S`, `-Y`, `-y`, and `-Z`.
`-d`	Enable/disable DMA (Direct Memory Access) for the drive, improving data transfer performance.
`-D`	Enable/disable on-drive defect management.
`-E`	Set SD/DVD drive speed by assigning a speed number. Common values are 2 or 4.
`-f`	Synchronize and flush the buffer cache for the device. Typically used before testing read speeds with `-t` and `-T`.
`-g`	Display the drive configuration, including size and starting offset.
`-h`	Display help message and exit.
`-i`	Show identification data collected from the drive during boot time.
`-I`	Fetch identification data directly from the drive, providing more details than the `-i` option.
`-k`	Get/set the keep_settings_over_reset flag for the drive.
`-K`	Set the drive’s keep_features_over_reset flag. Not all drives support this feature.
`-m`	Get/set the sector count for multiple sector I/O. Set to 0 to disable this feature.
`-M`	Get/set Automatic Acoustic Management (AAM) setting. Lower values reduce noise at the expense of performance. This feature is experimental.
`-n`	Get/set "ignore write errors" flag. Use cautiously after reviewing the driver source code.
`-r`	Get/set the read-only flag for the device. Once set, write operations will be disallowed.
`-S`	Set the standby timeout for the drive. A value of 0 disables standby mode.
`-T`	Measure cache read speed. This checks the speed of reading from the Linux cache without accessing the disk. Run multiple times for accuracy.
`-t`	Measure disk read speed. Similar to `-T`, but tests direct reads from the disk, bypassing cache. Combine with `-T` for detailed results.
`-u`	Get/set the interrupt-unmask flag for the drive. Can improve performance but may cause data corruption; use with caution.
`-v`	Display all drive settings, except those shown by `-i`.
`-w`	Reset the device.
`-W`	Enable/disable IDE drive write-caching. Improves performance but may risk data loss in power failures.
`-y`	Force the drive into low-power standby mode. The drive will spin down, reducing power consumption. Check status with `-C`.
`-Y`	Put the drive into low-power sleep mode, shutting it down completely. Use `-C` to check current power mode.
`-z`	Force the kernel to reread the partition table for the specified device.
`-Z`	Disable automatic power-saving functions for the drive.

hdparm command Examples

1. Command to display information of the hard drive: It is one of the most significant features as it unveils details of the hard disk drive, you need to use -I option and hard disk drive here.

$ hdparm -I /dev/sda

2. Command to display all the options:

$ hdparm -h

3. Command to test hard disk drive speed:

$ hdparm -t /dev/vdb

4. Command to measure hard disk cache read speed:

$ hdparm -T /dev/vdb

Output:

Command to measure hard disk cache read speed

5. Command to Enable read-ahead:

$ hdparm -A 1 /dev/sda

6. Command to switch the drive to the lowest degree of power management:

$ hdparm -B 254 /dev/sda

7. Command to get current settings:

$ hdparm -d /dev/sdX

8. Command to set DMA on for a device:

$ hdparm -d1 /dev/hda

9. Command to lower the noise created by some classical hard disk by lowering disk performance:

$ hdparm -M 128 /dev/sda

Conclusion

The hdparm command is a key tool for managing and optimizing hard drives in Linux, offering options to retrieve drive info, test read speeds, and adjust power settings. Caution is needed when modifying settings like DMA or power modes, as improper use can cause data corruption. Always consult the documentation and back up data before making changes.

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