SSD Trim: The Basic Knowledge of SSD You Cannot Miss

Nowadays, SSD drives are becoming more and more popular due to its advantages such as less power usage, faster, more reliable. However, when comes to SSD, not everyone knows it clearly especially for its terms taking trim SSD for example. How much do you know about SSD trim?

What is SSD Trim?

In order to know what SSD trim is, first you need to understand how SSD works. SSDs look like traditional hard drives, but they record data in different ways. Typically SSDs use NADA flash memory to store data and a flash controller to connect the memory with the host computer. For SSDs, data is stored in blocks. Each block consists of more than one file; we compare a block as a notebook and a file as one page of the notebook. For SSDs the data on notebook can be wiped when it is necessary. However, if you delete data on a page it isn’t really deleted, it is marked for deletion. This is because data can be only deleted on blocks. With time goes by, you find the blank pages are going to use up and you need more blank pages to store new data. But you can’t write directly on the page which you have written but you want to delete. At this time the marked pages will get together as a block and the whole block can be deleted.

When you want to delete data on block, this work depends on garbage collection which is the erase cycle for NADA flash memory. Garbage collection begins to work, when a block is full of data which include valid and invalid data. The valid data must be wiped to make room for new data, so the flash memory controller copies the valid data of the block to a previously erased block and ignores copying the invalid data of that block. Then the final step is to erase the original whole block, leaving the space for new data to be written.

The easing takes time and it can causes serious delays which rely on how much data your wants to delete. Fortunately, trim releases this problem. Because a trim command allows your operating system to find the marked pages before you need them and erase them clean. In this way, cleaning data in advance saves your time when you need to write data on the page again.

Attention: Garbage collection only available to your SSD, when it is idle. So you should make sure your computer doesn’t go to sleep when it’s idling. Besides, it takes Garbage Collection time to do its work, but when it is idle, your SSD will maintain its high level of performance.

Over-Provisioning (OP)

Before or during garbage collection, the copy of valid data is in two or more locations which are called write amplification. In order to store this extra data which isn’t counted by OS, the flash controller needs some spare space. This is called OP, and it is plays an important role in every NADA SSD.

Each SSD has the amount of OP. the different amount depends on tradeoffs made between the capacity of total storage and profit in performance and endurance. The less amount of OP in SSD, the user can store more information. But most of the users don’t know, not stretching OP area too thin makes you have lower write amplification, which convert to a higher performance during writes and longer endurance of the flash memory.

How to Enable Trim Support for Windows 8 and 7

Before you do:

  • Make sure your operating system support TRIM command.
  • Make sure your solid state drive's firmware support TRIM.

At first, check if the trim command has already active in Windows:

1. Open a Command Prompt window (run as administrator) Click on Start button → Click All Programs → Accessories → Command Prompt

2. Input fsutil behavior query DisableDeleteNotify at command prompt and press enter.

Two possible outcomes:

DisableDeleteNotify = 0 : TRIM is already available and working in Windows

DisableDeleteNotify = 1 :  TRIM is not available, do as step 3 to enable it

3. In order to enable SSD TRIM support in Windows, input following information at command prompt and press enter:
fsutil behavior set DisableDeleteNotify

From the above mentioned, you can clearly know that trim support is important for SSDs to have high performance. So in order to avoid slow writing time and to make you get out of depression, make sure that your SSD contains trim support.

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