What is TRIM for SSDs?

The short answer is TRIM is a command used by your operating system to optimize how your SSD is used and managed. It’s sort of a combination of organization and garbage collection for your drive. It isn’t exactly essential, but it does bring benefits to how your SSD performs and how long it lasts.

The good news is TRIM has been supported by Microsoft since on Windows 7 and that includes the more recent versions of Windows 10 and Windows 11. So, there’s a very good chance that you are covered already. Windows automatically runs the command in the background, generally on a weekly basis when you’re least busy, to keep the drive in top condition.

The TRIM command helps with erasing blocks of data that are no longer being used. It can help move some of the data that is sharing space with deleted files so that the freed-up space can be managed optimally.

You might think that this all happens when you delete a file, but due to the way SSDs operate, it isn’t actually the case. When you delete or remove a file in your operating system, the underlying data isn't really touched, merely flagged as being ready for deletion, but it isn’t changed until the next TRIM commend is run.

This is all down to how SSDs operate. When you write data to a drive it operates not on single cells but rather on pages. And when data is erased, this happens in terms of whole blocks, not individual cells or pages. Writing and erasing to the underlying cells also does a small amount of damage to them each time, which is why the SSD controller manages the whole process to improve the drive’s longevity.

So, the drives garbage collection in combination with TRIM helps to keep your drive’s data organized in the most optimal way possible.

While it may feel like there are some similarities between the two, TRIM and defragging are actually very different. When you defrag a hard drive, you organize the data blocks contiguously so that the data can be transferred quicker than that data being spread over the drive. This simply isn’t necessary when it comes to a solid state drive.

There are several ways of checking whether you have TRIM enabled, but possibly the easiest is to pop into Windows Explorer, right-click your SSD and select Properties from the drop-down menu. Next click on the Tools tab and then hit the Optimize button. While it doesn’t explicitly mention TRIM, you’ll know it’s turned on if you see the Scheduled optimisation option at the bottom of this window set to On.

There is another way, but it’s a little confusing, because it’s represented as a double negative. Open PowerShell, by right-clicking the Start button and selecting Terminal or PowerShell (depending on your version of Windows). Then at the prompt type:

fsutil behavior query DisableDeleteNotify

You’re looking for a response of 0 to show that it isn’t disabled. Yup confusing.

That’s it, you should now have a bit more of an understanding of what TRIM is, why it is used, and how to check whether it has been turned on in your operating system.