How to read the health of a hard drive or SSD and avoid losing data

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Almost no one thinks about their hard drive until it starts making strange noises, the PC lags, or a dreaded blue screen appears. However, regularly monitoring the health of your drives (HDD, SSD, or M.2) is one of the best ways to protect your computer, server, or NAS from unexpected problems.

Throughout this guide, you'll see, in great detail, how to read a disk's status, what its SMART parameters mean, what symptoms indicate a failure, and what tools are available in Windows, macOS, and Linux, including both built-in utilities and external programs like CrystalDiskInfo or smartmontools. The goal is for you to finish this article knowing how to detect a failing disk before it's too late.

Why is it so important to check the health of a disc?

A hard drive or SSD not only stores your documents, it also contains the operating system, programs, games, and often critical work data ; if the drive suddenly fails, the computer may become unusable, and recovering files from a disk will be complicated and expensive, if it is even possible.

Furthermore, all storage units have a limited lifespan : in mechanical HDDs, it is usually a few tens of thousands of hours of operation, while in SSDs the limit is measured in TBW (TeraBytes written) before the memory cells degrade and begin to fail.

Another key factor is that disk degradation is often silent ; bad sectors, read errors, or temperature problems can accumulate for months without you noticing anything serious… until one day the system stops booting or your files appear corrupted.

In professional environments (servers, NAS, critical workstations) the situation is even more serious, because a sudden disk failure can bring down services, cut off access to sensitive information, and cause financial losses , business interruptions, and even reputational problems for the company.

Symptoms that your hard drive or SSD may be failing

Before moving on to the tools, it is worth knowing the typical signs of a bad hard drive , because often the end user is the first to notice something strange while using the computer on a daily basis.

A very common indicator is abnormally slow performance : the system takes a long time to start up, open folders or load applications, or you notice that everything is choppy even though CPU and RAM usage does not seem high.

There are also more dramatic symptoms, such as random crashes, unexpected shutdowns, blue screens in Windows , or spontaneous restarts for no apparent reason, which are often due to read errors in disk sectors where system files reside.

In mechanical HDDs, it's advisable to pay attention to unusual noises: clicks, taps, or buzzing sounds ; these sounds can indicate problems with the spindle, platters, or read head, and are usually a bad sign if they are repeated continuously.

Another important warning sign is file and folder corruption : documents that suddenly won't open, damaged photos, errors when copying data, or system messages warning of disk errors, bad sectors, or damaged file system structures.

Finally, there are very clear physical or logical signs, such as significant overheating of the unit, BIOS/UEFI error messages when booting, disks that disappear from the system or that do not even allow the operating system to start.

What is SMART and why is it the basis for reading the health of a disk?

All modern hard drives, both traditional HDDs and SSDs and NVMe drives , integrate a technology called SMART (Self-Monitoring, Analysis and Reporting Technology) that acts as a kind of "black box" for the drive.

SMART internally monitors dozens of parameters related to disk reliability : rotation speed, read/write errors, reassigned sectors, spin-up times, CRC errors on the interface, temperature, operating hours, number of power-ups, etc.

Each of these attributes has a range of values ​​considered normal ; when any parameter falls outside these limits, SMART marks it as a potential problem and the disk firmware can inform the operating system to display warnings or launch a drive check.

The purpose of SMART is to warn you in advance that the drive may fail so you can back up your data and replace it before you're left stranded; ignoring these alerts usually results in data loss and drives that can only be sent to professional recovery companies.

To take advantage of SMART, your computer's BIOS or UEFI must have this function enabled, and the operating system or monitoring tools must be able to read the attributes ; nowadays, virtually all PCs, servers, and NAS devices are compatible.

How to read disk health with CrystalDiskInfo

One of the simplest and most visual ways to check the health of a disk in Windows is to use CrystalDiskInfo, a free and open-source utility that clearly displays the SMART status of drives.

The first thing you should do is download CrystalDiskInfo from the official CrystalMark website ; it is recommended to choose the basic version, without decorations or strange additions, and if possible the "portable" edition that does not require installation.

After downloading the .exe file, you can directly run the portable version or install it if you have chosen the classic installer ; in either case, the program will ask for administrator permissions the first time in order to access the drive information.

When you open CrystalDiskInfo, the application automatically analyzes the disks present in the system and shows you a main box with the "Health status" and temperature of the selected drive ; if everything is fine, you will see a "Good" status in blue.

If the disk is not perfect, CrystalDiskInfo will display a health percentage and may change the status color to yellow (Caution) or red (Bad) , indicating serious problems and that you should back up your data and consider a replacement as soon as possible.

Below the status and temperature, the tool offers a complete table with all SMART attributes : reassigned sectors, read errors, reassignment event count, pending sectors, uncorrectable errors, seek error rate, etc.

On the right side you will see data such as disk firmware, serial number, interface, supported standard, active features (including SMART), number of power-ons and operating hours , as well as read and write statistics in the case of SSDs.

CrystalDiskInfo also allows you to configure temperature and health alerts : you can adjust the thresholds to your liking, so that when the disk gets too hot or the health falls below a certain value, Windows displays a warning or a notification sounds.

From the Function menu you can customize the data update frequency, system tray integration, visual theme, font size, and even hide the serial number if you want to share screenshots without exposing that information.

Other disk monitoring programs and alternatives to CrystalDiskInfo

Although CrystalDiskInfo is one of the most popular options, there are many other tools for analyzing hard drive health , both free and paid, and with versions for different operating systems.

In the Windows ecosystem you can find utilities such as HDDScan, DiskCheckup or GSmartControl , which offer advanced SMART readings, surface tests, temperature monitoring and generation of detailed reports for technicians.

macOS offers solutions like iStat Menus , capable of displaying real-time temperatures, SMART statuses, and other performance parameters, integrating into the menu bar to keep everything readily visible.

Many security and maintenance suites include disk-specific modules; for example, some antivirus and system optimization tools integrate HDD/SSD health monitors that check SMART, detect bad sectors, and even help schedule defragmentation or optimization.

However, it's important to understand that no miracle program will fix serious physical damage to a disk ; these applications are useful as alert and diagnostic systems, but if SMART indicates serious problems, the priority should always be to save the data and repair the disk or replace the drive.

Checking disk health in Windows (SMART, CHKDSK and BIOS)

Without installing anything additional, Windows already offers several ways to check the basic SMART status and analyze the logical disk surface , both with a graphical interface and with command-line tools.

For a quick check, you can open Command Prompt (cmd) as administrator and run the command wmic diskdrive get status, which will read the SMART status and return "OK" if the disk is within normal parameters or "Pred Fail" when an imminent risk of failure is detected.

When the result is "OK", in principle there is no alert of immediate failure , although it is still advisable to perform periodic maintenance and backups; if "Pred Fail" appears, you have to assume that the unit may fail at any time and act quickly.

Another classic Windows tool is CHKDSK (Check Disk) , which checks the integrity of the file system, looks for logical bad sectors and, if instructed, attempts to repair errors in the partition's data structure.

To launch it, open cmd again as administrator and run chkdsk /f on the drive you want to analyze ; on the system disk it usually asks for permission to do so on the next restart, and it is important not to interrupt the process because the final report indicates what problems have been found and corrected.

Some manufacturers, such as HP, include their own utilities (HP Support Assistant, Dell Support, etc.) that offer specific hardware tests for the disk , such as read tests, surface checks, or complete diagnostics with a single click.

If you are comfortable with booting your computer, you can also enter the BIOS/UEFI and look for disk diagnostic options ; many modern computers allow you to run a quick or extended test on connected drives from there.

How to check disk health in macOS

On Macs, the standard tool for checking and repairing disks is Disk Utility , which comes pre-installed on the system and allows you to both check the file system and read the SMART status of internal drives.

To use it, go to Applications > Utilities and open Disk Utility, select the physical disk in the left panel (not just the partition) and look at the information that appears at the bottom of the window.

In that record you will see the result of the SMART test under a field called “SMART Status”; if it indicates “Verified”, the system considers that the unit is in good condition, while a status of “Fail” or messages with words like “fatal” or “error” are a sign that you should make a backup as soon as possible.

From the same tool you can use First Aid to try to repair logical errors in the file system , which is very useful if you detect problems mounting volumes, slowness when accessing folders or unexpected application closures.

Although Disk Utility provides a fairly clear overview, if you want to go further there are third-party tools for macOS that expand SMART information, record temperature and performance, and display historical graphs , which are very useful for long-term monitoring.

How to read the health of a disk in Linux using smartmontools

In Linux and Unix environments, the reference for working with SMART is the smartmontools package, which includes the smartctl (for occasional use) and smartd (monitoring daemon) utilities , available in virtually all distributions.

In Debian, Ubuntu and derivatives you can install it with sudo apt install smartmontools , while in other distros you will use the corresponding package manager (yum, dnf, pacman, zypper, etc.); it is also present in BSD-type systems.

Before running tests, it's a good idea to know what disks you have and where they are located, something you can see with commands like df -ho sudo fdisk -l , which list the drives and partitions available on your system.

SMART is always managed at the physical disk level, so you will work with paths like /dev/sda, /dev/sdb, /dev/nvme0n1, etc. , and not with partitions like /dev/sda1, /dev/sda2, etc.; this is an important detail for the commands to work correctly.

To check if a drive supports SMART and if it is enabled, you can run `sudo smartctl -i /dev/sda` ; if support is available but disabled, you can enable it with `sudo smartctl -s on /dev/sda` to start registering attributes.

Using `sudo smartctl -a /dev/sda` will give you a very complete report with all SMART attributes, current values, thresholds, raw counts, and event logs; this output is what you usually check when you want to do an in-depth diagnosis.

Smartctl allows you to run two main types of internal tests : short and long; the former runs in a few minutes and is used to detect basic problems, while the latter can take much longer because it scans the entire surface of the drive.

To start a short test you can use `sudo smartctl -t short /dev/sda` , and for a long check `sudo smartctl -t long /dev/sda` ; once finished, the results can be checked with `sudo smartctl -H /dev/sda` or by reviewing the full report again with `-a`.

On Linux servers and NAS devices, it is common to schedule these tests with cron, so that short tests are run, for example, once a week, and long tests once a month , always during off-peak hours to minimize the impact on performance.

Most important SMART attributes when evaluating a hard drive

When you start reading SMART reports, you'll find tables full of names and numbers that can be a little intimidating , but there are actually a few key attributes that are worth paying special attention to.

One of the most relevant is Reallocated_Sector_Ct (reallocated sector count) , which indicates how many bad sectors have been moved to reserve areas of the disk; a non-zero value is not automatically catastrophic, but if it grows over time it is usually a bad sign.

Also critical is Reallocated_Event_Count, which reflects the total number of reallocation events (whether successful or not); a continued increase in this counter suggests that the disk surface is starting to give out.

The Current_Pending_Sector attribute indicates how many sectors are pending reallocation ; these are sectors that have caused problems in reading or writing and that the disk is monitoring, waiting to decide whether they can be recovered or should be reallocated.

Another field to watch is Offline_Uncorrectable, which counts uncorrectable errors in offline operations; a high number means there are areas of the disk that can no longer be reliably accessed, and that directly impacts your data.

In mechanical HDDs, attributes such as Spin_Retry_Count (spin startup attempts) or Multi_Zone_Error_Rate (errors during writing in different zones) help detect problems in the motor or read heads before the failure becomes permanent.

NAS and servers: monitor disks on QNAP, Synology and others

In the world of NAS servers (QNAP, Synology, ASUSTOR, etc.), manufacturers usually integrate automatic disk health check systems , accessible from the web interface without having to use the terminal.

In QNAP, for example, you can go to "Storage & Snapshots" and then to "Storage / Disks" to see a summary of the status of all drives, with information on temperature, overall health, and SMART alerts.

If you go to the "Disk Condition" option, you can select each drive to see its detailed status , run quick or full tests, and schedule regular daily, weekly, or monthly checks at a time that suits you best.

In Synology, the path leads through the Storage Manager, HDD/SSD section , where you can select each disk to view data such as temperature, power-on time and the health status that the system assigns to the drive.

In these types of environments, in addition to monitoring individual disks, it is advisable to periodically check the status of the RAID or storage pool , since a multiple failure in configurations such as RAID 0 can result in the complete loss of data.

NAS administrators usually supplement these checks with backup strategies and appropriate RAID configurations (RAID 1, 5, 6, 10, ZFS with redundancy, etc.), so that the failure of a disk does not automatically imply loss of information.

How to extend the lifespan of your hard drives

Although no hard drive lasts forever, you can apply a series of practices to reduce the risk of premature failures and extend the lifespan of both HDDs and SSDs to the maximum , especially if you work many hours with them.

In the case of mechanical drives, it is essential to avoid shocks, strong vibrations, and sudden movements while the drive is running; an impact at the wrong time can physically damage the platters or the read heads.

Cooling is another key point: make sure your PC case or server chassis has good airflow , that the fans are working properly, and that there is no dust buildup blocking the inlets and outlets.

If you use the computer for gaming or heavy tasks for many hours, it may be a good idea to invest in a case with better ventilation, additional fans, or even specific cooling solutions to keep temperatures under control.

At the software level, in Windows it is advisable to schedule the defragmentation and optimization of drives (classic defragmentation on HDDs, TRIM optimization on SSDs) to run automatically, thus maintaining performance and reducing disk access stress.

In any case, the most important thing is not to rely entirely on the apparent "health" of the disk for your security : even if SMART says everything is perfect, there can always be a sudden failure, so regular backups (File History, Time Machine, backups to NAS or cloud, etc.) are mandatory.

Finally, when it's time to upgrade your hardware, it's worth choosing hard drives from reputable brands, suitable for the use you're going to give them (for example, specific models for NAS, for surveillance or for intensive use in servers) and with clear durability specifications.

Understanding how SMART works, knowing how to interpret the key parameters, and using tools like CrystalDiskInfo, smartmontools, Disk Utility, or your NAS management panels puts you in a much better position to detect when a disk starts to have problems, protect your data with backups, and plan hardware replacement without having to wait for disaster to strike.