How to read and analyze SMART data on SSDs and HDDs in Windows

Your computer might boot up in seconds and open programs at lightning speed, but if the hard drive where you store your data starts to fail, disaster strikes. Monitoring the real-time health of your HDD or SSD in Windows using SMART is one of those maintenance tasks that almost no one does, yet it can save you a lot of headaches and data loss.

The good news is that you don't need to be a systems technician to do it. With a few free tools , some simple commands, and a good understanding of what SMART attributes mean , you can tell if your mechanical or solid-state drive is healthy, if it's starting to show worrying symptoms, or if it's time to clone everything and replace the drive as soon as possible.

What is SMART and how far does it really go?

SMART stands for Self-Monitoring, Analysis, and Reporting Technology , meaning it's a self-monitoring and reporting technology integrated into virtually all modern HDDs and SSDs . The drive itself internally records metrics such as usage, errors, temperature, wear, power cycles, and many other details related to its reliability.

It's not a magic system that recovers lost files or physically repairs a broken disk; SMART works as an early warning system . It analyzes accumulated values ​​over time and, when certain thresholds are exceeded, indicates that the drive has a high probability of failing in the near future.

This technology originated in the 90s for mechanical hard drives and has since been adapted to SSDs and NVMe drives . While the underlying principles remain the same, the specific attributes used and how they are interpreted can vary considerably between HDDs and SSDs, and even between manufacturers.

It's also important to understand its limitations. SMART can only anticipate "predictable" failures , such as wear on the magnetic surface of an HDD, an increase in reallocated sectors, or the exhaustion of write cycles on an SSD. But it can't anticipate a power surge, a physical impact to the laptop, or a short circuit that renders the drive unusable in an instant.

Therefore, while SMART is a very useful tool for assessing the health of a drive, it does not replace regular backups or protect against sudden accidents . It is a key component within a basic data protection strategy, not an absolute safety net.

How Windows accesses SMART data

The positive aspect is that SMART is operating system independent: the data is generated by the drive itself, and Windows only reads it through commands or programs that rely on those same commands. This allows the use of both native tools and third-party applications.

In Windows, you have several ways to check SMART status, from the most basic to very detailed reports with dozens of attributes. Ideally, you should combine a quick check periodically with a more thorough review when you notice unusual symptoms (read errors, freezes, noises from mechanical disks, etc.).

WMIC command: quick disk status check

For an instant test without installing anything, Windows offers WMIC. It's a very simple command that checks each disk to see if its overall SMART status is correct or if it has detected serious problems.

The steps are: prepare the command prompt with administrative privileges and follow these steps.

• Open the search box from the Start menu, type cmd or "System Symbol".
• Right-click and choose "Execute as an administrator".
• Write wmic and press Enter.
• Then, write diskdrive get status (or directly wmic diskdrive get model, status (from the console without entering WMIC) and press Enter.

You'll see a list of drives and a simple result for each. If it says "OK," the drive hasn't triggered any critical SMART alerts . However, if you see messages like " Predicted Fail ," it means internal thresholds have been exceeded and the drive may be nearing failure; this is a sign to back up your data immediately and plan for its replacement.

CHKDSK: Checking and repairing logical errors

In addition to SMART status, Windows includes CHKDSK to detect and correct logical problems in the file system , locate bad sectors, and mark them as unusable. It doesn't rely directly on SMART, but it's an essential complementary tool when you suspect something is wrong with a drive.

To use it, open Command Prompt as administrator and run:

Command example: chkdsk C: /f /r /x

Where C: is the drive letter to analyze, /f corrects detected errors, /r locates bad sectors and attempts to recover data, and /x forces the volume to be unmounted. On NTFS drives you can also run:

Alternative option: chkdsk /scan

This type of analysis is useful when you notice unusual behavior (files that won't open, error messages when copying data, etc.). CHKDSK can repair logical damage, but not physical miracles : if the disk has mechanical problems or severely deteriorated NAND cells, it will only give you time to salvage what you can.

Programs to read and analyze SMART in Windows

While native commands serve as a first line of defense, specialized applications are what truly unlock SMART's full potential . They allow you to view each attribute, its current value, the worst recorded value, its failure threshold, and the raw data behind it.

CrystalDiskInfo: the most widely used free option

After downloading the executable from the official website (the standard edition is recommended), simply run or install it. When you open it, it automatically scans all drives and displays the first one by default ; if you have multiple drives, you can select each one from the tabs at the top.

In the upper left corner appears the "Health Status" box . If the background is blue and it says "Good" along with a high percentage, the disk is in good condition. If it drops to "Caution" or shows a low percentage, it's a sign of impending problems. A red reading indicates a high risk of failure.

Below you'll also see the drive's temperature , another key indicator of the longevity of both HDDs and SSDs. On the right, you'll find information such as firmware, serial number, interface (SATA, NVMe, etc.), transfer mode, drive letter, and whether SMART is enabled.

In another section, you'll find the total data read and written (Total Host Reads/Writes) , the rotational speed for mechanical drives, the number of power cycles, and the total operating hours . With these numbers, you can compare, for example, the TB written against the TBW (Terabytes Written) rating stated by your SSD manufacturer.

At the bottom of the window appears the SMART attributes table. Each row represents an attribute (numeric identifier and name), with columns for Current Value, Worst, Threshold, Raw Data, and a status indicator . These are typically displayed in white when everything is fine and change to yellow or red when concerning values ​​are detected.

CrystalDiskInfo also allows you to configure temperature and health status alarms . If certain limits are exceeded, it can display visual alerts or play sounds. You can also adjust the refresh rate, hide serial numbers, integrate the program into the system tray, and customize the theme and font size.

Other tools for viewing SMART in Windows

CrystalDiskInfo isn't the only solution. There are other solutions with different approaches for reading and interpreting SMART data in Windows and monitoring disk health.

HD Tune combines health monitoring, SMART attribute reading, performance measurement, and surface analysis. The "Health" tab displays the attributes; white indicates everything is fine; yellow or red indicates warnings or imminent failures. "Error Scan" lets you run a quick scan to locate serious errors or a slow scan that goes sector by sector (ideal for large HDDs, although it can take many hours).

Another very comprehensive option is Hard Disk Sentinel . It focuses on continuous monitoring of HDDs and SSDs, interprets SMART attributes, and displays a very detailed health and estimated lifespan diagnosis. It also allows you to configure alerts, export reports, analyze temperatures, and run tests. However, its free version is quite limited compared to the paid version, and the interface can be overwhelming for novice users.

If you're looking for something open source, GSmartControl relies on smartmontools and offers a graphical interface for viewing SMART attributes and running short, long, or in-depth tests . It's very accurate and cross-platform, but requires some familiarity with these concepts to get the most out of it.

How to interpret the most important SMART attributes

When looking at attributes , in almost any monitoring software you will see, for each attribute, something like this:

• Identifier (ID): number between 1 and 250 that identifies the attribute (e.g., 5 for reassigned sectors, 9 for hours of operation, 194 for temperature…).
• Price: normalized score (100, 200 or other scale according to the manufacturer) that starts from a high value in a new unit and decreases with wear.
• Worst: lowest value the attribute has had since it began to be recorded.
• ThresholdIf the normalized value falls below this limit, SMART marks the attribute as failed.
• Raw Data: raw counter with the actual data (number of sectors, hours, cycles, degrees, etc.).
• Flags or type: indicates whether the attribute is critical for failure prediction, whether it is only informative, whether it is updated in real time or during specific tests.

Not all attributes carry the same weight. Some are clearly critical, while others are mere statistics . These are the ones you should monitor very closely, for both HDDs and SSDs:

Reallocated Sector Count (ID 5) . When a sector on an HDD or a block on an SSD becomes unreliable, the drive marks it as bad and redirects the data to a spare sector/block. The counter reflects how many reallocations have occurred. If the number starts to increase over time, it indicates wear or deterioration of the magnetic surface or NAND flash memory.

Pending/unstable sector count . These are sectors that have experienced read errors and are "under observation," awaiting reassignment if they fail again. While SMART algorithms aren't always conclusive on this data, a gradual increase often foreshadows problems.

Uncorrectable errors reported . This counter shows errors that could not be corrected by either the Error Correction Code (ECC) or retries. It is one of the most universal attributes among manufacturers, and an increase in this number is a clear sign of potential data loss.

In the specific case of SSDs, there are key attributes related to NAND wear that should be monitored:

Erase fail count . Measures the number of failed cell erase attempts. An increasing value indicates that the flash memory is nearing the end of its useful life.

Wear Leveling Count . This represents an estimate of the overall health of the SSD, calculated based on program/erase cycles per block and expected lifespan. It is usually expressed as a percentage of remaining life or a percentage of life consumed.

Device temperature (ID 194) . Sustained temperatures above 60°C reduce lifespan and increase the likelihood of errors. For many SSDs, exceeding 70°C is considered critical and can even void the warranty. Keeping the drive properly cooled is just as important as maintaining the CPU or GPU.

Specific SMART attributes and recommendations from Crucial

Crucial, through Storage Executive , highlights several attributes of its SATA and PCIe SSDs:

Attribute 202: Percentage of remaining useful life (or percentage of used life) . When the drive is new, this value is typically 100% (remaining life) or 0% (used life). As you write data and the NAND blocks wear down, this percentage adjusts. Reaching 0% remaining life (or 100% used life) does not mean the SSD will immediately fail ; it means it has reached the guaranteed lifespan according to the JEDEC data retention specifications.

JEDEC defines a minimum data retention of one year for client SSDs without power at approximately 30°C when the drive is within its rated lifespan. Beyond that point, the data retention capacity without power may decrease (six months, three months, etc.), but the firmware compensates with increased ECC, retries, background data maintenance, and replacement of degraded blocks with internal spares.

Crucial SSD Attribute 5: Retired NAND Blocks . This counts how many blocks, or even "superblocks" (groups of several blocks), have been retired because they are no longer reliable. The number can increase due to natural wear and tear or failures during data erasure and relocation operations. As long as the count increases slowly and there are sufficient spare blocks, the drive can remain stable.

Attribute 180: Unused Reserved Block Count . This is the other side of the coin: the spare blocks that are still available to be used when bad blocks are removed. When this attribute reaches zero, the firmware typically puts the SSD into read-only mode to safeguard the data, but no further data can be written.

Attribute 210: Pages recovered using RAIN . RAIN (Redundant Array of Independent NAND) is a type of internal RAID within the SSD. It uses parity redundancy between memory chips to correct errors and extend lifespan. If the RAIN correction count starts to rise frequently, it usually indicates heavy use of redundancy to maintain data integrity , which can impact performance and be a sign that the drive is nearing the end of its useful life.

Attribute 174: Unexpected power loss count . This value is generally informative. Each abrupt shutdown (pulling the cord, power outage, hanging up without a clean shutdown) increases the counter. A very high number may point to electrical problems or poor shutdown habits , not necessarily an SSD defect.

Attribute 194: Cover Temperature . Crucial displays both the current and maximum recorded temperature. For most of its SSDs, the recommended operating range is 0°C to 70°C. Regularly exceeding 65-70°C should be corrected as soon as possible with better ventilation or heatsinks, because high temperatures accelerate NAND wear and may void the warranty.

Crucial also points out an important detail: third-party utilities can misinterpret these attributes if they don't follow the manufacturer's exact definitions . A power-on hour counter, for example, could be mistakenly labeled as "program errors" and trigger nonexistent fault alerts. That's why they recommend always using Storage Executive for their models, as it understands each attribute and its actual threshold.

When to worry: critical SMART symptoms and errors

Beyond the numbers, listening to your team is key. Many HDD or SSD problems manifest themselves in everyday use long before the drive disappears from the system. Combining practical symptoms with SMART readings is the best way to decide if it's time to replace the drive.

Visible indicators that usually appear:

• Unexpected program closures that access disk intensively (video editing, games, databases, virtual machines).
• Error messages when saving, copying, or moving filesespecially if they always affect the same folders or drives.
• On mechanical discs, strange noises like clicking, buzzing, or chirping which they didn't do before.
• Blue Screens in Windows with codes related to storage or file systems.
• Excessive access time when opening programs or browsing folders, even after the system has just started.
• Files that "disappear" or become corrupted without you having deleted or touched them.
• Very high temperatures in the area where the discs are mounted.
• Drives that sometimes do not appear when turning on the PC or that disappear during use.

If you add to this the fact that in WMIC, CrystalDiskInfo or the manufacturer's software you see states like "Pred Fail", "Caution", very low health percentages or critical counters that rise rapidly , the prudent thing to do is:

• Do it immediately a complete backup of important data.
• Avoid heavy writing tasks (gaming, editing, mass copying) on ​​that disk.
• Plan to purchase a replacement drive and decide whether to clone the disk or perform a clean installation.

Many high-end SSDs, when wear is detected beyond certain limits, enter a read-only "pre-failure" mode . This allows you to recover all your data but prevents you from writing anything else. If you encounter this situation, it's time to back up everything you need without delay and replace the drive.

Performance tests to detect hidden problems

Another way to uncover potential faults is to subject the drive to controlled performance tests. A healthy SSD or HDD should be able to maintain consistent speeds within the expected range for its interface and model . If the results are significantly lower or the test is interrupted by errors, it's another indication that something is wrong.

A commonly used tool for this is CrystalDiskMark , from the same developer as CrystalDiskInfo. It reads and writes sequential and random blocks of data of varying sizes to measure MB/s read/write speeds.

If, when running the test, you see speeds far below what the manufacturer advertises, very high response times, or even crashes and errors during the test , you need to investigate: in an SSD, it could indicate degraded memory chips or firmware problems; in an HDD, excessive fragmentation , bad sectors, or simply that the drive is nearing the end of its lifespan.

These tests do not replace SMART readings, but they help confirm whether the problems you see in the numbers translate into abnormal performance in real-world use.

Knowing how to read and analyze SMART for SSDs and HDDs in Windows, using tools like CrystalDiskInfo, HD Tune, Hard Disk Sentinel or the manufacturer's official software, and complementing all of this with utilities like WMIC and CHKDSK, allows you to go from "crossing your fingers" to having real control over the health of your drives and, above all, over the security of your data.