What is SMART? Advantages, Disadvantages & More

What is (SMART) Self-Monitoring Analysis and Reporting Technology?

Self-Monitoring Analysis and Reporting Technology, or SMART refers to a fault-detection technique designed by IBM. This system uses different devices called sensors and methods to detect and notify the health of the disks of a hard drive.

Technically, apart from a diagnostic method to find the health status of a hard drive, SMART also signifies the interface between the storage device and the Basic Input Output System (BIOS) of the platform.


  • Self-Monitoring Analysis and Reporting Technology signifies the monitoring, fault detection, and maintenance technology found in the hard drives used by computers that sends notifications in advance about the faults.
  • SMART is usually enabled by default in the BIOS and processes information from the storage device. It also determines whether or not to notify the user by sending a warning note about the likely failure of the hard drive.
  • There can be as many as 30 measured values on one single ATA hard disk, called the attributes. A few of the SMART attributes affect the health of the hard drive directly or indirectly and some provide statistical information.
  • Most of the modern hard disk drives including IDE, Serial ATA, and SCSI come with this specific feature built in. However, the attributes in all may not be the same because it is certainly not a universal standard.
  • The SMART notifications help the users know about their hard drive and its performance along with the quick actions they need to take such as copying or backing up data on another drive to handle a possible failure.

Understanding (SMART) Self-Monitoring Analysis and Reporting Technology

What is SMART

Typically, the diagnostic technology developed by IBM, Self-Monitoring Analysis and Reporting Technology or SMART, was introduced with the Advanced Technology Attachment 3 (ATA 3) specification.

It was designed to be used in their mainframe drives to provide advance warnings about its failures.

Initially, it was called the Predictive Failure Analysis, which is the main objective of this technology in the real sense.

However, based on this concept and technology, Compaq designed and submitted IntelliSafe to the ATA/IDE standards committees. The resulting standard was named SMART.

Mostly, SMART analyzes mechanical attributes to predict whether or not the hard drive is falling short of its tolerance.

Depending on the level of wear and tear of the hard drive, SMART can also predict the residual lifespan so that the users can make a decision whether they would take a backup of their data and continue using the drive or replace it.

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However, the technology cannot sense accidental or unexpected failures such as:

  • Physical manhandling
  • Failure of electronic components
  • Power surges

Still, it is a very useful feature to have and therefore most of the major Hard Disk Drive (HDD) and Solid State Drive (SSD) manufacturers include it in their system designs.

These companies include and are not limited to:

  • IBM
  • Western Digital
  • Maxtor
  • Crucial
  • Quantum
  • Seagate
  • Fujitsu

SMART is a part of the firmware of the hard drive, so it is something that you cannot download. It is typically found between the hard drive and the BIOS.

What is (SMART) Self-Monitoring Analysis and Reporting Technology

Disk Self Test (DST) Types

Based on the features included, a hard drive can perform different types of SMART tests for different requirements such as:

  • Short DST
  • Long or Extended DST
  • Selective DST
  • Conveyance DST

Working Process

At the most elementary level, this technology operates on specific sensors and techniques to scan and monitor the health of the hard drive and then distinguishes into two broad categories such as:

  • Predictable failures
  • Unpredictable failures

Predictable failures comprise about 60% of total hard drive failures that are used in consumer systems and include:

  • Degradation of the storage surface for data
  • Mechanical wear

Unpredictable failures are often the results of improper handling and misuse of hardware and therefore cannot be reasonably predicted.

Therefore, SMART typically concentrates on the predictable failures in particular. This is because these failures can be tracked easily and documented automatically.

SMART Fields

While in action, SMART examines the current status of the hard disk drives using several sensors to get measured values. These values are processed further by means of different algorithms which also modify the equivalent attributes based on the results.

Typically, these attributes have the following fields:

  • Identifier – It is usually a byte or a number, but names and additional textual descriptions may also be provided about the attributes by a few applications.
  • Data – This field of 6 bytes stores raw measured values received from the counter or sensor that are further processed by the hard disk algorithm. Different parts such as the low-, middle-, and high-16 bits of this value may sometimes contain different types of information.
  • Threshold – This single-byte field indicates the limit value of the attribute.
  • Value – This one-byte field reflects the relative current health status of the attribute and is typically estimated by the algorithm with the help of the raw data. This value is usually high on a new hard disk and it gradually decreases during its lifetime.
  • Worst – This is also a single-byte field containing the smallest value that has been found ever during the past lifetime of the hard disk drive.
  • Status flags – This field indicates the primary purpose of the attribute which can be either critical, where the failure can be predicted, or statistical, where it does not affect the condition of the hard drive directly.
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You may note at this point that more information may be displayed by the software with reference to these fields and may even help in evaluating or managing the attributes.

The Math Behind

The measured values or attributes are considered correct when the figure in the Value field is equal to or greater than that of the Threshold field.

Failure of the hard drive is predicted if, for a critical attribute, this is not true. The attribute determines the problem and the hard disk is considered to be bad and needs immediate replacement.

At this point, the SMART feature sends warnings to the users before they boot the operating system.

On the other hand, a failure of the hard drive cannot be predicted by the attribute if its Threshold is 0. This is because the Value cannot be less than 0.

Therefore, mathematically, an attribute is perfect in cases where this particular inequality is TRUE: A – f(r) >= C, where:

  • ‘A’ indicates the theoretical maximum value or the best value of the attribute possible.
  • ‘f’ indicates the linear function for calculating the decrement based on the raw (r) values. In most cases, raw value is multiplied by a constant, B.
  • ‘C’ indicates the threshold level, which is typically vendor-specific.

The problem with this calculation is that the A, B, C, and f function or values cannot be defined precisely. This is because they may vary from one model to another or even on two separate hard disks made by the same manufacturer.

Another notable downside is that the evaluation of the attributes is made independently, ignoring the relationship between them.

Status Check

Though SMART will notify about the issues 0n the hard drive, it is always a good idea to check the status of it manually and regularly, which can be done both on a Windows and a Mac computer.

On a Windows computer, you can check it by following these steps:

  • Go to the search box
  • Type “Performance Monitor” in the box
  • Open the utility

You will now have to create a system diagnostic report in the following way:

  • Click on the “Data Collector Sets” tab
  • Double-click on the “System” tab
  • Look for System Diagnostics and Performance options
  • Right-click on the “System Diagnostics” option
  • Select “Start”
  • Click on “Reports” at the bottom of the list after the checking is complete
  • Double-click on the “System” tab
  • Click on the resulting item to see the report
  • Look down to the “Basic System Check” section
  • Click on “Disk Checks”
  • Click on the + button in front of it
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On a Mac, you can check the SMART test results as follows:

  • Open “Finder”
  • Click on “Applications”
  • Click on “Utilities”
  • Open “Disk Utility”
  • Click on the particular drive

The SMART status will be displayed as either “Verified” or “Failing.”

What Does SMART Do?

The primary function of SMART is to monitor the hard drive, its performance and detect the signs of its failure early and automatically.

And, in most cases, this technology will also notify you about the specific issue on the hard drive that it has detected.

The SMART utility will typically review all the vital IDs automatically to indicate the good or bad health of the hard drive in your computer system.

Ideally, SMART can show different attributes and information depending on the type of drive being used.

However, it is not an actual standard and therefore the meanings of each attribute may vary from one manufacturer to another.


  • It helps in managing the drive.
  • It helps in ensuring proper repairs.
  • It allows better life cycle management and enhances the life of the drives.
  • It offers convenience of use.
  • It ensures higher sustainability.
  • It offers more security.
  • It increases the efficiency of the system.
  • It saves a considerable amount of money and time.


  • Incorrect selection of thresholds may result in lack of failure prediction.
  • Vendor-specific methods do not reveal the real health of the hard disks.
  • Weight of attributes can provide misleading information.
  • Incorrect use of a high threshold value may ignore critical issues.
  • Relationship between the attributes is ignored.
  • Need using the right software to get the correct feedback.
  • Incorrect use of software may also lead to sensor and temperature issues.
  • Incorrect drivers for hard disk controllers may also provide incorrect information.
  • Inappropriate use of data and hardware provides wrong threshold values.
  • Sometimes the hard disk controllers may provide incomplete test results.


Self-Monitoring Analysis and Reporting Technology is very useful for the hard disk drives because it lets the users know about the future issues in the drive early.

The technology is a part of the firmware within the hard disk drive that uses different methods and sensors to conduct different types of SMART tests.

About Dominic Cooper

Dominic CooperDominic Cooper, a TTU graduate is a computer hardware expert. His only passion is to find out the nitty gritty of all computers since childhood. He has over 12 years of experience in writing, computer testing, and research. He is not very fond of social media. Follow Him at Linkedin

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