contrib/smart/smart.8

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.\" Note: The date here should be updated whenever a non-trivial
.\" change is made to the manual page.
.Dd February 14, 2026
.Dt SMART 8
.Os
.Sh NAME
.Nm smart ,
.Nm diskhealth
.Nd monitor disk health from a storage device via SMART
.Sh SYNOPSIS
.Nm
.Op Fl dhitvx
.Oo Fl a Ar page:attribute Ns Oo , Ns Ar page:attribute Oc Ns ... Oc
.Op Fl Fl debug
.Ar device
.Nm diskhealth
.Op Fl Dhitvx
.Oo Fl a Ar page:attribute Ns Oo , Ns Ar page:attribute Oc Ns ... Oc
.Op Fl Fl debug
.Ar device
.Sh DESCRIPTION
The
.Nm
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,
.Nm
normalizes entries using the format:
.Bd -literal
	<Page ID>    <Attribute ID>    <Value>    <Thresholds>
.Ed
.Pp
Fields are tab-delimited by default, but the command can output
data in any format supported by
.Xr libxo 3 .
.Pp
Because ATA does not have log pages,
.Nm
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
.Fl Fl threshold
option are:
.Pp
.Bl -dash -compact -offset indent
.It
Status flags (byte offset 1, 2 bytes)
.It
Nominal attribute value (byte offset 3, 1 byte)
.It
Worst Ever attribute value (byte offset 4, 1 byte)
.El
.Pp
Additionally,
.Nm
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.
.Pp
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,
.Nm
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
.Fl Fl threshold
option.
.Pp
SCSI devices can support a number of log pages which report drive
health.
The command will report the following pages:
.Pp
.Bl -dash -compact -offset indent
.It
Write Errors (Page ID 2 / 0x2)
.It
Read Errors (Page ID 3 / 0x3)
.It
Verify Errors (Page ID 5 / 0x5)
.It
Non-medium Errors (Page ID 6 / 0x6)
.It
Last N Errors (Page ID 7 / 0x7)
.It
Temperature (Page ID 13 / 0xd)
.It
Start-stop Cycles (Page ID 14 / 0xe)
.It
Informational Exceptions (Page ID 47 / 0x2f)
.El
.Pp
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
.Fl Fl threshold
option.
.Pp
The following options are available:
.Bl -tag -width "-d argument"
.It Fl a Ar page:attribute , Fl Fl attribute= Ns Ar page:attribute
A comma-separated list of attributes to display.
If page is missing, display the matching attribute from any page.
.It Fl d , Fl Fl decode
Decode the attribute ID values.
This is the default when invoked as
.Nm diskhealth .
.It Fl D , Fl Fl no-decode
Do not decode the attribute ID values.
This is the default when invoked as
.Nm .
.It Fl h , Fl Fl help
Prints a usage message and exits.
.It Fl i , Fl Fl info
Print general device information.
.It Fl t , Fl Fl threshold
Also print the threshold values.
.It Fl v , Fl Fl version
Print the version and copyright.
.It Fl x , Fl Fl hex
Print the values in hexadecimal.
.It Ar device
An explicit device path
.Pq Pa /dev/ada0
or GEOM provider
.Pq Pa ada0
.
.El
.El
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
Print all SMART READ DATA and SMART STATUS including the
threshold values for ATA drive ada0.
.Pp
.Dl # smart -t ada0
.Pp
Print only attribute ID 5 ("Reallocated Sectors Count") for
ATA drive ada0.
.Pp
.Dl # smart -a 5 ada0
.Pp
Print attribute IDs 5 ("Reallocated Sectors Count") and 171
("SSD Program Fail") for ATA drive ada0.
.Pp
.Dl # smart -a 5,171 ada0
.Pp
Print all health pages supported by SCSI device da0 including:
.Bl -dash -compact -offset indent
.It
Write Errors
.It
Read Errors
.It
Verify Errors
.It
Non-medium Errors
.It
Last N Errors
.It
Temperature
.It
Start-stop Cycles
.It
Informational Exceptions
.El
.Pp
.Dl # smart da0
.Pp
Print all Health log page entries in hexadecimal for NVMe
device nda0.
.Pp
.Dl # smart -x nda0
.Sh DIAGNOSTICS
The command may fail for one of the following reasons:
.Bl -diag
.It "No output displayed"
The device does not support health data.
.It "CAMGETPASSTHRU ioctl failed"
.Nm
relies on
.Xr cam 4
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
.Xr nvd 4
NVMe driver instead of the
.Xr nda 4
driver.
.El
.Sh SEE ALSO
.Xr libxo 3 ,
.Xr cam 4 ,
.Xr nda 4 ,
.Xr nvd 4
.Sh AUTHORS
This
utility was written by
.An Chuck Tuffli Aq Mt chuck@FreeBSD.org .
.Sh BUGS
Probably.