---
name: "nvme_smart_log"
section: "2"
platform: "linux"
package: "libnvme-dev"
version: "1.13-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nvme_smart_log"
---

# nvme\_smart\_log(2)

SMART / Health Information Log (Log Identifier 02h)

## NAME

struct nvme\_smart\_log - SMART / Health Information Log (Log Identifier 02h)

## SYNOPSIS

struct nvme\_smart\_log {\
     **\_\_u8 critical\_warning;**\
     **\_\_u8 temperature\[2\];**\
     **\_\_u8 avail\_spare;**\
     **\_\_u8 spare\_thresh;**\
     **\_\_u8 percent\_used;**\
     **\_\_u8 endu\_grp\_crit\_warn\_sumry;**\
     **\_\_u8 rsvd7\[25\];**\
     **\_\_u8 data\_units\_read\[16\];**\
     **\_\_u8 data\_units\_written\[16\];**\
     **\_\_u8 host\_reads\[16\];**\
     **\_\_u8 host\_writes\[16\];**\
     **\_\_u8 ctrl\_busy\_time\[16\];**\
     **\_\_u8 power\_cycles\[16\];**\
     **\_\_u8 power\_on\_hours\[16\];**\
     **\_\_u8 unsafe\_shutdowns\[16\];**\
     **\_\_u8 media\_errors\[16\];**\
     **\_\_u8 num\_err\_log\_entries\[16\];**\
     **\_\_le32 warning\_temp\_time;**\
     **\_\_le32 critical\_comp\_time;**\
     **\_\_le16 temp\_sensor\[8\];**\
     **\_\_le32 thm\_temp1\_trans\_count;**\
     **\_\_le32 thm\_temp2\_trans\_count;**\
     **\_\_le32 thm\_temp1\_total\_time;**\
     **\_\_le32 thm\_temp2\_total\_time;**\
     **\_\_u8 rsvd232\[280\];**\
 };\

## Members

- critical\_warning

  This field indicates critical warnings for the state of the controller. Critical warnings may result in an asynchronous event notification to the host. Bits in this field represent the current associated state and are not persistent (see *enum nvme\_smart\_crit*).

- temperature

  Composite Temperature: Contains a value corresponding to a temperature in Kelvins that represents the current composite temperature of the controller and namespace(s) associated with that controller. The manner in which this value is computed is implementation specific and may not represent the actual temperature of any physical point in the NVM subsystem. Warning and critical overheating composite temperature threshold values are reported by the WCTEMP and CCTEMP fields in the Identify Controller data structure.

- avail\_spare

  Available Spare: Contains a normalized percentage (0% to 100%) of the remaining spare capacity available.

- spare\_thresh

  Available Spare Threshold: When the Available Spare falls below the threshold indicated in this field, an asynchronous event completion may occur. The value is indicated as a normalized percentage (0% to 100%). The values 101 to 255 are reserved.

- percent\_used

  Percentage Used: Contains a vendor specific estimate of the percentage of NVM subsystem life used based on the actual usage and the manufacturer's prediction of NVM life. A value of 100 indicates that the estimated endurance of the NVM in the NVM subsystem has been consumed, but may not indicate an NVM subsystem failure. The value is allowed to exceed 100. Percentages greater than 254 shall be represented as 255. This value shall be updated once per power-on hour (when the controller is not in a sleep state).

- endu\_grp\_crit\_warn\_sumry

  Endurance Group Critical Warning Summary: This field indicates critical warnings for the state of Endurance Groups. Bits in this field represent the current associated state and are not persistent (see *enum nvme\_smart\_egcw*).

- rsvd7

  Reserved

- data\_units\_read

  Data Units Read: Contains the number of 512 byte data units the host has read from the controller; this value does not include metadata. This value is reported in thousands (i.e., a value of 1 corresponds to 1000 units of 512 bytes read) and is rounded up (e.g., one indicates the that number of 512 byte data units read is from 1 to 1000, three indicates that the number of 512 byte data units read is from 2001 to 3000). When the LBA size is a value other than 512 bytes, the controller shall convert the amount of data read to 512 byte units. For the NVM command set, logical blocks read as part of Compare, Read, and Verify operations shall be included in this value. A value of 0h in this field indicates that the number of Data Units Read is not reported.

- data\_units\_written

  Data Units Written: Contains the number of 512 byte data units the host has written to the controller; this value does not include metadata. This value is reported in thousands (i.e., a value of 1 corresponds to 1000 units of 512 bytes written) and is rounded up (e.g., one indicates that the number of 512 byte data units written is from 1 to 1,000, three indicates that the number of 512 byte data units written is from 2001 to 3000). When the LBA size is a value other than 512 bytes, the controller shall convert the amount of data written to 512 byte units. For the NVM command set, logical blocks written as part of Write operations shall be included in this value. Write Uncorrectable commands and Write Zeroes commands shall not impact this value. A value of 0h in this field indicates that the number of Data Units Written is not reported.

- host\_reads

  Host Read Commands: Contains the number of read commands completed by the controller. For the NVM command set, this value is the sum of the number of Compare commands and the number of Read commands.

- host\_writes

  Host Write Commands: Contains the number of write commands completed by the controller. For the NVM command set, this is the number of Write commands.

- ctrl\_busy\_time

  Controller Busy Time: Contains the amount of time the controller is busy with I/O commands. The controller is busy when there is a command outstanding to an I/O Queue (specifically, a command was issued via an I/O Submission Queue Tail doorbell write and the corresponding completion queue entry has not been posted yet to the associated I/O Completion Queue). This value is reported in minutes.

- power\_cycles

  Power Cycles: Contains the number of power cycles.

- power\_on\_hours

  Power On Hours: Contains the number of power-on hours. This may not include time that the controller was powered and in a non-operational power state.

- unsafe\_shutdowns

  Unsafe Shutdowns: Contains the number of unsafe shutdowns. This count is incremented when a Shutdown Notification (CC.SHN) is not received prior to loss of power.

- media\_errors

  Media and Data Integrity Errors: Contains the number of occurrences where the controller detected an unrecovered data integrity error. Errors such as uncorrectable ECC, CRC checksum failure, or LBA tag mismatch are included in this field. Errors introduced as a result of a Write Uncorrectable command may or may not be included in this field.

- num\_err\_log\_entries

  Number of Error Information Log Entries: Contains the number of Error Information log entries over the life of the controller.

- warning\_temp\_time

  Warning Composite Temperature Time: Contains the amount of time in minutes that the controller is operational and the Composite Temperature is greater than or equal to the Warning Composite Temperature Threshold (WCTEMP) field and less than the Critical Composite Temperature Threshold (CCTEMP) field in the Identify Controller data structure. If the value of the WCTEMP or CCTEMP field is 0h, then this field is always cleared to 0h regardless of the Composite Temperature value.

- critical\_comp\_time

  Critical Composite Temperature Time: Contains the amount of time in minutes that the controller is operational and the Composite Temperature is greater than or equal to the Critical Composite Temperature Threshold (CCTEMP) field in the Identify Controller data structure. If the value of the CCTEMP field is 0h, then this field is always cleared to 0h regardless of the Composite Temperature value.

- temp\_sensor

  Temperature Sensor 1-8: Contains the current temperature in degrees Kelvin reported by temperature sensors 1-8. The physical point in the NVM subsystem whose temperature is reported by the temperature sensor and the temperature accuracy is implementation specific. An implementation that does not implement the temperature sensor reports a value of 0h.

- thm\_temp1\_trans\_count

  Thermal Management Temperature 1 Transition Count: Contains the number of times the controller transitioned to lower power active power states or performed vendor specific thermal management actions while minimizing the impact on performance in order to attempt to reduce the Composite Temperature because of the host controlled thermal management feature (i.e., the Composite Temperature rose above the Thermal Management Temperature 1). This counter shall not wrap once the value FFFFFFFFh is reached. A value of 0h, indicates that this transition has never occurred or this field is not implemented.

- thm\_temp2\_trans\_count

  Thermal Management Temperature 2 Transition Count

- thm\_temp1\_total\_time

  Total Time For Thermal Management Temperature 1: Contains the number of seconds that the controller had transitioned to lower power active power states or performed vendor specific thermal management actions while minimizing the impact on performance in order to attempt to reduce the Composite Temperature because of the host controlled thermal management feature. This counter shall not wrap once the value FFFFFFFFh is reached. A value of 0h, indicates that this transition has never occurred or this field is not implemented.

- thm\_temp2\_total\_time

  Total Time For Thermal Management Temperature 2

- rsvd232

  Reserved