Defragmentation of SSD, Harmful or Not?

Defrag SSD

It’s a normal situation everybody has experienced at least once. Read and write circles on your computer appear to be slower and slower. One of the usual procedures is the defragmentation of your hard drive.

But is that a good idead with modern electronics?

If you are using an SSD (Solid State Drive) you should rather quickly discard the idea. It doesn’t matter, if it’s an internal or external SSD, also.

But why can defragmentation cause damage to an SSD and what alternatives are there?

What is defragmentation?

A classic hard disk drive (HDD) has moving components in the form of a circuit board and a read/write head that travels over the disk drive. All data is stored in blocks on the disk. From time to time, the user deletes files. When this happens, gaps appear on the disk. This process is called fragmentation (fragment = leftover).

Although these gaps can be filled by new files, sometimes these gaps are too small for certain data. If this is the case, the operating system divides the files into several blocks. The result: reading without interruption is not possible. The hard drive’s reading head has to jump back and forth and realign itself again and again. This is a time consuming process.

With defragmentation, the file structure on the hard disk is completely rearranged, and the existing gaps are closed. This means that files can be accessed more quickly again, because the mechanical arm has less way of travel.

No advantage through defragmentation of an SSD

The main difference between an SSD and an HDD is that the SSD has no moving parts. Instead, the way it works is identical to that of a USB stick or SD memory card. Data is stored in bits on storage chips, rather than on a magnetical disc. Read head and physical simply do not exist. The memory cells of SSDs are read and written by the SSD controller – this happens at the same high speed all the time. Defragmenting the SSD is therefore neither necessary nor sensible, because the physical conditions do not match.

SSD defragmentation potentially harmful

SSDs have a variety of advantages: they are faster, quieter and less prone to fail due to mechanical defects than HDDs. One major disadvantage of the SSD is that only limited write and read cycles are possible. If the maximum number of write accesses is exceeded, certain symptoms can indicate an SSD failure. It is also possible that the memory will suddenly stop working altogether.

To increase the lifetime of individual SSD memory cells, intelligent SSD controllers ensure that each cell is used in the same ratio. If one memory cell were to be filled before the next one was written to, damage would be inevitable. The classic hard drive defragmentation process interferes with the operation mode of the SSD controllers. This can result in a permanent damage to the SSD.

Alternative Solution : Optimise SSD

If you notice a decrease in SSD performance, you can analyse the drive via the Windows system application (app) “Defragment and optimise drives” and activate an automatic optimisation. This process is not connected to defragmentation at all. Instead, Windows optimises the performance of an SSD via TRIM command.

The TRIM command is the link between the Windows file structure and the SSD’s management organisation. By doing so, the Windows operating system shows the controller which files have been deleted. When cleaning up the flash memory, the controller does not have to recopy file and the SSD speed increases.

This is only necessary if your run Windows XP or lower on your SSD. Starting with Windows 7, TRIM is automatically activated.


Image credit: Markus Spiske on Unsplash