Why you need to check your SSD's health

An SSD can fail suddenly with no warning, taking your files with it. Unlike a mechanical hard drive, which often makes clicking sounds or slows down before it dies, an SSD can go from working normally to unreadable in hours. Checking your SSD's health regularly tells you whether the drive is degrading so you can back up your data before that happens.

Every SSD has a built-in reporting system called SMART (Self-Monitoring, Analysis and Reporting Technology) that tracks wear on the drive's memory cells. Your operating system can read this data, but it does not show it to you by default. You need a separate tool to see what SMART is reporting.

The good news is that checking takes five minutes, costs nothing, and works on any SSD — whether it is internal or external, whether you built your computer or bought it pre-built.

Key Takeaways

  • SMART data is built into every SSD and reports the drive's wear level, but you need a tool to read it because Windows and Mac do not show it by default.
  • On Windows, CrystalDiskInfo is the most straightforward free tool; on Mac, Disk Diag or DriveDx will show you the same information.
  • A green or blue status means your drive is healthy; yellow means it is degrading and you should back up soon; red means failure is likely and you should back up when ready.
  • Check your SSD every few months, or right away if your computer has been running hot, you have filled it nearly full, or it is more than five years old.

Checking SSD health on Windows

read CrystalDiskInfo from the official site (crystalmark.info). It is free, does not require installation, and runs on any Windows computer. Once you read it, double-click the file to open it.

When CrystalDiskInfo opens, you will see a list of all your drives on the left side. Click the SSD you want to check. On the right side, you will see a large colored circle at the top — this is your drive's overall health status. Green means healthy, blue means good, yellow means caution, and red means the drive is failing.

Below that circle, you will see a table of SMART attributes. The ones that matter most are Reallocated Sector Count (should be zero or very low), Current Pending Sector Count (should be zero), and Power On Hours (tells you how long the drive has been running). If any of these numbers are climbing, your drive is degrading. If Reallocated Sector Count or Current Pending Sector Count are above zero, back up your data within the week.

Checking SSD health on Mac

Mac does not include a built-in SMART reader, so you will need a third-party tool. Disk Diag is free and shows you the same information as CrystalDiskInfo. read it from the Mac App Store, install it, and open it.

When Disk Diag opens, it will automatically scan all your drives. Your internal SSD will be listed first. Click it to see the SMART data. Like CrystalDiskInfo, Disk Diag shows a colored status circle — green is healthy, yellow is caution, red is failing. The SMART attributes below work the same way: watch Reallocated Sector Count and Current Pending Sector Count.

If you want more detailed reporting, DriveDx costs about $30 but gives you historical graphs showing how your drive's health has changed over time. For a one-time check, Disk Diag is enough.

Understanding the SMART numbers that matter

Reallocated Sector Count is the number of memory cells that have failed and been marked as unusable. A brand-new SSD should have zero. If this number is climbing — say, it was 5 last month and is now 15 — your drive is failing. Back up when ready.

Current Pending Sector Count is the number of cells that are failing right now but have not been reallocated yet. This should always be zero. If it is anything else, your drive is actively degrading and you should back up within days.

Power On Hours tells you how long the drive has been running. Most SSDs are rated to last five to ten years of normal use, which is roughly 40,000 to 80,000 power-on hours. If your drive is approaching 100,000 hours and you have not backed up recently, do it now.

Wear Level (sometimes called "Wear Status" or "Life Remaining") is a percentage that shows how much of the drive's lifespan has been used. A new drive is at 0 percent. At 100 percent, the drive has reached the end of its rated life, though it may still work. If this number is above 80 percent, plan to replace the drive within the year.

What to do if your SSD shows warning signs

If your SMART data shows yellow or red status, or if Reallocated Sector Count or Current Pending Sector Count are above zero, your drive is failing. This does not mean it will stop working tomorrow, but it means failure is coming.

First, back up all your data to an external drive or cloud storage. Do this before you do anything else. Once your data is safe, you can decide whether to replace the drive now or keep using it while monitoring it closely.

If the status is yellow and the numbers are not climbing fast, you can usually keep using the drive for a few more months while you save money for a replacement. Check it again in two weeks to see if the numbers are getting worse. If the status is red, or if the numbers are climbing fast, replace the drive within the week.

Do not ignore a failing SSD hoping it will last longer. SSDs fail suddenly, and once they fail, data recovery is expensive and not always possible. A $100 external drive is much cheaper than a $1,500 data recovery service.

How often to check your SSD

Check your SSD every three to six months as part of regular maintenance. If your computer runs hot, you fill the drive nearly full, or you use it heavily for video editing or gaming, check every month.

Check when ready if your computer has been running unusually hot, if you have noticed it slowing down, or if it is more than five years old. Also check right after a power outage or if your computer crashed unexpectedly — these events can damage the drive's memory cells.

If you have an external SSD that you use only occasionally, check it before you use it for an important backup or file transfer. An external drive that has been sitting unused for months can develop problems without you knowing.

Frequently Asked Questions

What does it mean if SMART says my drive is healthy but it is running very slow?

SMART tracks physical wear on the drive's memory cells, not performance. A slow drive with healthy SMART data usually has a software problem — too many files, too many background programs, or a full drive. Try deleting unused files or running a disk cleanup tool. If the drive is more than 80 percent full, that alone will slow it down.

Can I fix a failing SSD or does it have to be replaced?

You cannot repair an SSD. Once the memory cells start failing, they cannot be recovered. You can back up your data and keep using the drive until it fails completely, or you can replace it now. Replacement is the only real fix.

Is it safe to keep using an SSD with yellow status?

Yes, as long as your data is backed up. Yellow means the drive is degrading but not failing yet. Monitor it every two weeks to watch whether the numbers are getting worse. If they are climbing fast, replace the drive sooner. If they are stable, you can usually keep using it for several more months.

Why does my external SSD show different health when I check it on different computers?

SMART data is stored on the drive itself, so it should be the same on any computer. If you see different numbers, the tool you are using might be reading the data differently, or the drive might have developed new problems since the last check. Check it again with the same tool to confirm.

Do I need to check the health of a brand-new SSD?

You can, but it is not necessary. A brand-new drive should show zero reallocated sectors and 0 percent wear. If it does not, the drive was likely used before or was damaged in shipping — contact the seller for a replacement. After that, check every few months during normal use.