Many people defragment regularly as part of their PC maintenance routine, and it's a good habit to get into. At least if the computer has a regular hard drive (HDD). But systems with solid state drives or SSDs cannot be defragmented. Information portal makeuseof.com speakWhy.
First, it is necessary to clarify what defragmentation is. When saving files to your hard drive, they don't always fit in one cell – the drive will store them wherever there's free space. Sometimes this “space” can be scattered at different physical points on the hard drive's spinning platter.
What is described above is called fragmentation. But gradually, as files on your hard drive are downloaded, deleted, and modified, it will start to become more fragmented. The read/write head must move across disk locations to assemble a single file, which slows down the loading process. Defragmentation allows you to reorganize scattered file fragments into solid blocks: the tool moves them so that each file stays in a permanent location. As a result, the system reduces the distance the read/write head needs to travel – and, accordingly, reduces startup time.
Mechanical failure of the hard drive is essentially the only reason the defragmentation process exists. If the drive reads data using moving parts, then proper file organization can actually have a significant impact on performance.
But SSDs or solid state drives work very differently. They store files not on spinning disks but on flash memory. SSDs can quickly access any storage cell, regardless of its location, so fragmentation does not slow down the drive. In fact, defragmentation does not benefit SSDs at all. Even if files are scattered across a solid state drive, the person at the monitor won't notice a difference in speed.
Additionally, defragmentation can cause damage to the SSD. Flash memory cells are designed to last for a limited number of write cycles before they are exhausted. Every time you defragment, the system forces the disk to overwrite huge amounts of data for no reason, thereby wasting memory resources. The fact is that SSDs have built-in anti-wear measures that help evenly distribute file writes across different cells. Defragmentation interferes with this process and causes some areas of the disk to overwrite files.
So why does Windows still have a defragmentation utility? The answer is simple – she is no longer the same. Microsoft renamed this tool “Disk Optimization” for good reason: it automatically detects the type of drive and recommends various maintenance measures. When an SSD is detected, the utility does not defragment the drive, but executes the TRIM command, created specifically for flash drives.
TRIM works as follows. When deleting a file, the operating system marks the drive blocks where it is located as empty. On a regular hard drive, this is not a problem because it can overwrite old data immediately. But SSDs must erase blocks before writing new files to it, which slows performance over time. TRIM tells the SSD which blocks contain deleted data so it can be formatted during periods of inactivity. This way, when you need to load something new, the disk will have empty blocks available without you having to format it first.
