{"id":102687,"date":"2025-09-16T21:48:04","date_gmt":"2025-09-16T21:48:04","guid":{"rendered":"https:\/\/www.auslogics.com\/en\/articles\/?p=102687"},"modified":"2025-10-08T15:21:53","modified_gmt":"2025-10-08T15:21:53","slug":"ssd-trim-and-garbage-collection-what-are-they-and-how-do-they-work","status":"publish","type":"post","link":"https:\/\/www.auslogics.com\/en\/articles\/ssd-trim-and-garbage-collection-what-are-they-and-how-do-they-work\/","title":{"rendered":"SSD TRIM and Garbage Collection: What Are They, and How Do They Work?"},"content":{"rendered":"

My first time using a gaming laptop with an SSD exposed the shortcomings of hard disk drives. Windows booted faster, and game launches were quicker. But SSDs are not immune to performance drops.<\/p>\n

I learned about TRIM and garbage collection (GC) after experiencing unusual slowdowns and delays when starting games and copying large files.<\/p>\n

Activating TRIM resolved my issue because I had optimization turned off across my system.<\/p>\n

Alongside other SSD optimization<\/a> practices, my drive now fires on all cylinders, and I have absolutely no issues with performance. I can also rest easy about drive health. So what are TRIM and garbage collection? This article will break everything down and show you how to get the best out of your hard drive, regardless of the type of SSD you have<\/a>.<\/p>\n

\r\n\t
TL;DR<\/div>\r\n\t
<\/p>\n

\ud83c\udff7\ufe0f TRIM is a Windows command that tells your SSD which pieces of data it should erase.<\/p>\n

\u2195\ufe0f Garbage collection is a process initiated by the SSD to rearrange data and free up space.<\/p>\n

\ud83d\udce5 SSDs write and read data at the page (smallest storage unit) level but can only delete data by erasing blocks (groups of pages).<\/p>\n

\ud83e\uddf9 During garbage collection, valid pages are moved into new blocks so that old blocks can be erased and freed up for new data.<\/p>\n

\ud83d\uddc3\ufe0f Without TRIM, garbage collection will shuffle invalid data since it does not know which pages should be deleted.<\/p>\n

\u2705 TRIM is enabled by default on Windows.<\/p>\n

<\/>_ <\/b>You can use the Command Prompt to verify whether TRIM is turned on. You can also use a CMD command to enable or disable TRIM.<\/p>\n

\ud83d\udcbb Third-party applications like Auslogics SSD Optimizer can also run TRIM operations.<\/p>\n

<\/div>\r\n<\/div>\r\n\n

How Do SSDs Write and Delete Data?<\/h2>\n

To understand the meaning and purpose of TRIM and garbage collection, you need a background understanding of how SSDs work.<\/p>\n

Every SSD stores data as electrical charges in NAND flash cells, which enables it to read and write files faster than HDDs<\/a>. A group of cells makes up a page, and a group of pages makes up a block. Whenever you save a file to your SSD, the file is broken down into pieces that fit into pages.<\/p>\n

If a page on an SSD is 4 KB (it can be 16 KB or larger), a 10 MB file will occupy about 2,560 pages on the SSD. The number of pages that make up a block varies by SSD. It can be 64, 128, 256, or more.<\/p>\n

You can read and write to a page just fine, but you can\u2019t erase at that level. SSDs can only erase at the block level. However, the SSD must first move pages it considers valid out of a block before erasing the block.<\/p>\n

TRIM and garbage collection are required to identify the files you want to delete and move valid pages out of the blocks that are earmarked for erasure.<\/p>\n

\r\n\t
Need help with your PC?<\/div>\r\n\t
Try our Ask a Question<\/a> service — our experts will diagnose and resolve your PC issues completely free of charge.<\/div>\r\n<\/div>\n

What Is SSD TRIM?<\/h2>\n

TRIM is a command that helps your SSD identify invalid data. Here\u2019s why that matters. When you delete a file, it doesn\u2019t just vanish from your drive. Windows simply marks the pages containing the data as available. But before you can write to those \u201cavailable\u201d pages again, their host blocks must be deleted.<\/p>\n

\r\n\t
\r\n\t\t
<\/div>\r\n\t\t
PRO TIP<\/div>\r\n\t\t
<\/div>\r\n\t<\/div>\r\n\t
<\/p>\n

The term \u201cTRIM\u201d is not an abbreviation. It is a command for the ATA interface<\/a>, which is written in capital letters. Other storage interfaces have different names for the same process, but TRIM is the popular and widely accepted term.<\/p>\n

For example, eMMC\/UFS storage (for smartphones and tablets) uses the Discard command, while NVMe drives use the Data Set Management command with the Deallocate <\/i> attribute. <\/div>\r\n<\/div>\r\n\n

Without TRIM, the SSD still thinks the data you deleted is valid, but it has to make the space it currently occupies available, per your operating system\u2019s instructions.<\/p>\n

The SSD\u2019s controller moves the \u201cdeleted\u201d data to a new block so that the old block can be erased and prepared for new writes.<\/p>\n

This process slows down the drive over time.<\/p>\n

Microsoft addressed this issue in Windows 7 by adding native TRIM support. The OS could now inform the SSD that your deleted files are no longer valid. That way, the drive can safely delete the data when it is idle.<\/p>\n

\r\n
\r\n \"The\r\n <\/div>\r\n
<\/div>\r\n<\/div>\n

The process of moving valid data and deleting old blocks is called garbage collection.<\/p>\n

\r\n
Download Auslogics SSD Optimizer<\/div>\r\n
Your safe and effective SSD performance guard, the app will optimize data placement on your solid-state drive, help clear disk space, monitor drive health and extend its service life.<\/div>\r\n
\r\n Download for Free<\/a>\r\n Learn More<\/a>\r\n <\/div>\r\n
\r\n Privacy Policy<\/a>  \r\n EULA<\/a>\r\n <\/div>\r\n<\/div>\r\n\n

How Does Garbage Collection Work?<\/h2>\n

As I mentioned earlier, SSDs don\u2019t delete blocks containing valid pages. So they run a housekeeping process called garbage collection. The operation involves gathering still-valid pages from unfilled blocks, copying them into fresh blocks, and then erasing the old blocks.<\/p>\n

\r\n
\r\n \"TRIM\r\n <\/div>\r\n
<\/div>\r\n<\/div>\n

That \u201cshuffling\u201d is how the SSD makes space for new writes. TRIM helps by telling the SSD ahead of time which pages are truly garbage (invalid). That way, the SSD will copy only the valid pages and leave \u201cgarbage\u201d pages behind in blocks that will be later deleted.<\/p>\n

It makes the process lighter, faster, and less punishing on the drive. It also speeds up hard drive performance<\/a> and prolongs SSD lifespan.<\/p>\n

Garbage collection on SSDs comes in these two flavors:<\/p>\n