Should You Defrag SSD? Here's the Best Answer You Want!

Defrag/Defragmentation often comes into play when Windows users want to speed up performance and optimize space usage of the HDD (Hard Disk Drive), making it quicker and easier for the system to retrieve files.

Plenty of Windows users wonder whether they should defrag SSD, if there's any difference between defragging SSD and HDD, and what the disk fragmentation means. This post revolves around the questions above.

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Reddit discussions on defrag SSD

Whether an SSD should be defragmented caused heated discussions in the post on Reddit, where some netizens and geeks shared their opinions and points of view on this topic. You can view the following Reddit post and certain answers may come to your mind.

Should I really not defrag my SSDs/NVMEs?
by u/SendMeAvocados in pcmasterrace

Why is disk fragmentation from?

“Do I need to defrag SSD?” Before answering the question, we'd better do a quick review of sectors and blocks on HDD and why disk fragmentation occurs.

A sector is the smallest physical storage unit of an HDD, usually 512 bytes, while a block is a logical unit consisting of multiple sectors, the size of which is defined by the file system. In HDDs, the file system allocates storage space in blocks, and the system prefers storing a new file in continuous blocks. 

If a file does not occupy the entire block, other files cannot occupy the remaining block space. In other words, a block can only belong to one file and cannot be shared by multiple files, otherwise it will lead to data confusion or overwriting. For example, when the block size is 4KB and a 5KB file occupies 2 blocks (4KB + 1KB), other files cannot use the remaining 3KB of the second block.

When there's no sufficient and continuous free space for a new file, the system is forced to split the file into pieces and store them in small and non-continuous spaces, making the file fragmented. When you delete a file on an HDD, the space (blocks) it once occupied are marked as free and available for new data, thus the free space becomes fragmented as well.

Should you defrag SSD?

The answer is uncontroversially NO, and the reasons lie in the main difference between SSD (Solid State Drive) and HDD (Hard Disk Drive).

An HDD uses the traditional technology that relies on the frequent mechanical movement of spinning magnetic platter, and the read/write head. Therefore, when an HDD is severely fragmented, its read/write head has to move more to access all the pieces of a fragmented file.

Unlike an HDD, fragmented files hardly affect an SSD, as the SSD does not have parts that physically move, and it simply stores your data by using the flash memory chip, and data is directly accessed through the electronic signal.

Additionally, the advent of NAND flash memory, TRIM technology, and automatic optimization algorithm enables the system to manage the storage and unused space on SSD automatically and efficiently.

Conclusion

Now we can conclude that defragmentation helps increase HDD read and write speeds by rearranging files into continuous blocks and reducing the number of read/write head movements.

On the contrary, if you defrag SSD, it will cause unnecessary wear, as defragmentation requires frequent data movement, resulting in a large number of unnecessary erase/write operations, accelerating wear on SSD and shortening its lifespan. You may want to know how to check SSD health on Windows: SSD Health Check: Why & How to Do It in Windows OS?

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