Now that solid-state drives (SSDs) are becoming an affordable alternative to hard drives, certain terms are being used quite often. One of these terms is "TRIM support." To understand what TRIM support is, you first need to understand how solid-state drives work. SSDs use NAND flash memory to store and transfer information. This flash memory is created up of small "pages" and groups of pages are called "blocks." When you tell your computer to delete a page on the solid-state drive the page isn't actually deleted - it is merely marked for deletion. This is because data can only be deleted in blocks. You cannot delete individual pages on an SSD. Later on, when you tell your computer that you need the space, the pages marked for deletion are grouped into a block and the whole block is wiped clean. This process slows down the solid-state drive when it is writing.

Let us explain in a different way.

Imagine, if you will, that you have a stack of blank papers on your desk at work. Each workday you keep the papers with important information on them, but get rid of the unnecessary papers, like the one you doodled on during a boring meeting, by putting them in the "To Be Recycled" tray on your desk. It's not worth going all the way down to the recycling center for a few sheets of paper, so you wait until you have a stack that is worth the travel time.

Eventually, you run out of blank paper. Since you have a project due that day, it is now time to use the paper from the "To Be Recycled" tray. You take out your eraser and get to work. Erasing takes a lot of effort, so you decide to only clean up a portion of the stack to tide you over for a while. Eventually you will run out of paper again and you'll have to erase another portion, but you plan on crossing that bridge when you come to it. 

That is why solid-state drives slow down while writing after prolonged use. They have to clean the files marked for deletion before they can be written on, and erasing takes time. This can cause serious delays, depending on how much data you're trying to save and how much needs to be deleted. Luckily, TRIM alleviates this problem and is supported on many of the SSDs and operating systems made today.

 A TRIM command enables your operating system to find the marked pages before you need them and wipe them clean. Cleaning these data pages beforehand saves you time when you need to write on the data pages again. It's like you have your own recycling guy next to your desk, recycling the pieces of paper as they come.

In order to work correctly, TRIM has to be supported by both the solid-state drive and the operating system you are using. When both the OS and the SSD support TRIM individual pages can be cleaned and your solid-state drive will be informed that the pages are now blank and can be written on. This kind of cleaning and communication is essential to keep your drive performing to the best of its abilities.

SSDs such as the OCZ Vertex 2, the OCZ Agility 2 and the Corsair Force, as well as most of the other storage devices on our solid-state drive review, all feature native TRIM support. TRIM support is essential for an SSD to run the way it should. To avoid slow writing times, and to save yourself from frustration, make sure that the solid-state drive you are buying includes TRIM support.

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