With a lot of more modern computers using SSD’s (Solid State Hard Drives), one question I often get asked is if you need to defragment a SSD. That’s a good question because up until now, pretty much everyone has heard of defragmenting a PC.

So why do we defragment a hard drive in the first place? Well, I won’t go into super detail here since you can read about it online, but basically it’s because spinning hard drives taker longer to read data that is “fragmented” or stored in multiple locations on the hard disk. Since spinning hard drives read and write data sequentially, it will take longer for the hard drive to read a file if parts of the file are located on different parts of the disk as compared to being located altogether in one unit/space.

ssd defrag

So defragmenting a normal spinning hard drive can be useful depending on the size of your drive, the number of files you have stored and the size of those files. Now the question becomes is defragmenting useful if the hard drive has no physical moving parts?

hdd

Well, the answer to that question is pretty easy once you understand the difference between an SSD and a HDD. An SSD is basically non-volatile flash memory, which you are probably used to using in your digital camera, etc. An SSD is fast because it randomly accesses memory instead of sequentially like an HDD. SSD’s are great, but there is one huge caveat that most hard drive manufacturer’s never mention about SSDs and that’s their lifespan.

LifeSpan of SSDs

Because of the way they are built, an SSD wears down every time they are write accessed. If you have read reviews of SSDs before, you have probably read about how an SSD will get slower if you benchmark it after completely filling the drive and then erasing it. With a HDD, you would never have that problem. Most people mistakenly think SSDs are safer than HDDs because they have no moving parts. This is not true. Flash memory has a very finite lifespan and the more it is used, the more quickly it will fail.

So back to the question of defragmenting. When you defrag a hard drive, especially a SSD, it will end up causing tons of small write accesses, which will reduce the lifespan of the hard drive. And since data is not being read sequentially, it doesn’t matter if the file is stored in a hundred different places, the performance will remain the same.

So, no, you should not defrag an SSD. And performing one will actually reduce the life of your drive. All of the SSD manufacturer’s know of this problem and they have come up with an optimization technique with the use of the TRIM command.

Currently, with HDDs and SSDs, if you delete some data on the hard drive, the operating system does not actually remove the content from the disk, it just deletes the pointer to the address and therefore “deletes” the data. That’s probably why you’re heard of secure delete or government security file deletion, which actually overwrites the deleted data with gibberish so no one can use advanced tools to read data later on.

This issue of data not actually being deleted is what causes the lifespan of SSDs to be reduced. If the drive knew which areas of memory didn’t contain any important data, it could simply re-use it for new data. The TRIM command is supported by the latest SSDs and will optimize the hard drive so that it reduces the number of writes/deletions and therefore extends the life of your SSD significantly.

If you’re in the market to buy an SSD, make your choice very carefully. You want a hard drive that supports the TRIM command.

There are a lot of other SSDs that support the TRIM command, but you have to check with the manufacturer. Note that Windows 7/8/10 natively supports the TRIM command for hard drives that support it, so you don’t have to do anything. Older versions of Windows do not support the TRIM command. In the case of Windows XP and Vista, the OS cannot even tell the difference between an SSD and a HDD, so it’s best to turn off the Disk Defragmenter.

You can also use third party programs that support TRIM to run on systems not running Windows 7/8/10. If you don’t believe everything I’ve said, then you can check out this post from a more reliable source that details exactly why it’s not a good idea to defrag a SSD:

http://www.oo-software.com/en/docs/whitepaper/ood_ssd.pdf

If you have a different opinion or something to add, please feel free to add a comment! Enjoy!