---
name: "diskhealth"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/diskhealth"
---

# diskhealth(8)

monitor disk health from a storage device via SMART

## NAME

**smart**, **diskhealth** – monitor disk health from a storage device via SMART

## SYNOPSIS

**smart** \[**-dhitvx**\] \[**-a** *page:attribute*\[,*page:attribute*\]...\] \[**-****-debug**\] *device*

**diskhealth** \[**-Dhitvx**\] \[**-a** *page:attribute*\[,*page:attribute*\]...\] \[**-****-debug**\] *device*

## DESCRIPTION

The **smart** command allows the user to monitor the various information reported by Self-Monitoring, Analysis and Reporting Technology (SMART) present on most ATA, SCSI, and NVMe storage media. Because the structure of this information varies across protocols, **smart** normalizes entries using the format:

```
	<Page ID>    <Attribute ID>    <Value>    <Thresholds>
```

Fields are tab-delimited by default, but the command can output data in any format supported by [libxo(3)](/libxo/3.md).

Because ATA does not have log pages, **smart** uses the Command Feature field value in place of the log page ID. For SMART READ DATA, this value is 208 / 0xd0. Note that devices choose which attribute ID values they support, their descriptions, and the format of the data. The three values displayed with the **-****-threshold** option are:

- Status flags (byte offset 1, 2 bytes)

- Nominal attribute value (byte offset 3, 1 byte)

- Worst Ever attribute value (byte offset 4, 1 byte)

Additionally, **smart** reports the value of the SMART STATUS command (Command Feature field value 218 / 0xda). As this command does not return any data, the command represents this entry with a synthetic attribute ID of 0, and it uses the command status (0 or 1) as the attribute value.

NVMe devices support the SMART/Health log page (Page ID 2 / 0x2). The data returned in this log page is not structured as attribute IDs. Instead, **smart** uses the byte offset of each field as the attribute ID. For example, byte 3 is the Available Spare. Thus, for NVMe, attribute ID 3 is Available Spare. Note that NVMe health data does not include threshold values, and as a result, the command will ignore the **-****-threshold** option.

SCSI devices can support a number of log pages which report drive health. The command will report the following pages:

- Write Errors (Page ID 2 / 0x2)

- Read Errors (Page ID 3 / 0x3)

- Verify Errors (Page ID 5 / 0x5)

- Non-medium Errors (Page ID 6 / 0x6)

- Last N Errors (Page ID 7 / 0x7)

- Temperature (Page ID 13 / 0xd)

- Start-stop Cycles (Page ID 14 / 0xe)

- Informational Exceptions (Page ID 47 / 0x2f)

Note that all log pages are optional, and a particular drive may not support all these pages. For SCSI devices, the Attribute ID maps to the SCSI parameter code defined by the command. Parameter codes are integer values from 0 to N, and, by themselves, are ambiguous outside the context of a particular log page. Note that SCSI health data does not include threshold values, and as a result, the command will ignore the **-****-threshold** option.

The following options are available:

- **-a** *page:attribute*, **-****-attribute=***page:attribute*

  A comma-separated list of attributes to display. If page is missing, display the matching attribute from any page.

- **-d**, **-****-decode**

  Decode the attribute ID values. This is the default when invoked as **diskhealth**.

- **-D**, **-****-no-decode**

  Do not decode the attribute ID values. This is the default when invoked as **smart**.

- **-h**, **-****-help**

  Prints a usage message and exits.

- **-i**, **-****-info**

  Print general device information.

- **-t**, **-****-threshold**

  Also print the threshold values.

- **-v**, **-****-version**

  Print the version and copyright.

- **-x**, **-****-hex**

  Print the values in hexadecimal.

- *device*

  An explicit device path (*/dev/ada0*) or GEOM provider (*ada0*)

## EXIT STATUS

The **smart** utility exits 0 on success, and \>0 if an error occurs.

## EXAMPLES

Print all SMART READ DATA and SMART STATUS including the threshold values for ATA drive ada0.

```
# smart -t ada0
```

Print only attribute ID 5 ("Reallocated Sectors Count") for ATA drive ada0.

```
# smart -a 5 ada0
```

Print attribute IDs 5 ("Reallocated Sectors Count") and 171 ("SSD Program Fail") for ATA drive ada0.

```
# smart -a 5,171 ada0
```

Print all health pages supported by SCSI device da0 including:

- Write Errors

- Read Errors

- Verify Errors

- Non-medium Errors

- Last N Errors

- Temperature

- Start-stop Cycles

- Informational Exceptions

```
# smart da0
```

Print all Health log page entries in hexadecimal for NVMe device nda0.

```
# smart -x nda0
```

## DIAGNOSTICS

The command may fail for one of the following reasons:

- No output displayed

  The device does not support health data.

- CAMGETPASSTHRU ioctl failed

  **smart** relies on [cam(4)](/cam/4.md) to retrieve data from devices and will display this message if the device does not have a passthrough driver. This can happen, for example, if the system uses the [nvd(4)](/nvd/4.md) NVMe driver instead of the [nda(4)](/nda/4.md) driver.

## SEE ALSO

[libxo(3)](/libxo/3.md), [cam(4)](/cam/4.md), [nda(4)](/nda/4.md), [nvd(4)](/nvd/4.md)

## AUTHORS

This utility was written by Chuck Tuffli ⟨*chuck@FreeBSD.org*⟩.

## BUGS

Probably.