Disk Utility Trim Cleanup macOS Sierra

In a previous article I went through how to use the Disk Utility app to run First Aid on the Fusion Drive in my iMac. I was running macOS El Capitan at the time. I performed the same procedure on my new internal SATA Crucial SSD on the iMac. Here is what I discovered.


The Trim Command

Just in case you do not know what the Trim Command is on SSD drives here is a typical definition:

A trim command (known as TRIM in the ATA command set, and UNMAP in the SCSI command set) allows an operating system to inform a solid-state drive (SSD) which blocks of data are no longer considered in use and can be wiped internally. Trim was introduced soon after SSDs were introduced.
– via www.google.com

It coordinates the operating system with the SSD (Solid State Drive) regarding cleanup of data blocks. This keeps your SSD running smoothly and fast. With a standard spinning hard drive the operating system has built in features that monitor unused space. You can use software programs like Drive Genius to “Defrag” spinning hard drives which cleans them up. You do not “Defrag” an SSD. The Trim Command takes care of keeping the SSD clean.

Disk Utility Trim

Obviously, when you run First Aid on an Apple Fusion Drive in the Disk Utility app it performs a Trim cleanup on the SSD portion of the Drive. This really does speed up the machine. However, when you run it on a standard SSD like the Crucial MX300 in my iMac,there is no spinning HD attached, it just runs on the full SSD itself.

Keep in mind to do this properly you need to boot your machine up externally; either using the Recovery Partition (Restart, hold down Command ⌘ + “R”) or boot from another drive attached to the Mac. I used my Tech Drive which has macOS Sierra on it along with several utility apps.

When you bring up Disk Utility you will get a window similar to this one. As you can see I have lots of drive partitions attached to my iMac:


To run the Trim Command you have to select “Macintosh HD” (or whatever your HD is actually named) and then click on the “First Aid” button:


When you do this, Disk Utility runs First Aid on your SSD. It runs several repair and cleanup routines during this SSD check. One of the last ones is the Trim Command:


Once First Aid is completed you just have to Restart the machine and boot back into macOS Sierra.

I can confirm that running this Trim Command cleanup really does speed up my internal SATA installed Crucial SSD. It is a little snappier. No, I am not imagining it. I don’t think you need to do this more than once every few months, but it is worth the hassle for sure. You might mention that if Trim is turned on then it should be working all the time, and you would be right. But, somehow running First Aid in the Disk Utility app seems to force a little extra cleanup. Don’t ask me why that works, but it does.


If you are running a Fusion Drive or straight SSD setup in your Mac I encourage you to try this procedure. It is worth your time and it will not harm anything.