Should an SSD be defraged?

The general feeling is no. There is also a school of thought that suggests that it could damage the drive.

SSDs don’t have a mechanical working so there shouldn’t be any gain in performance.

It works in older drives because the heads had to move back and forth and sit and wait for data to get into position underneath it. Since SSDs don’t worry about that it’s more like reading memory.

Newer drives benefit from large cache memory so defragmenting is less of an issue now than it was a few years ago.

And, as @Lightlyseared points out, SSDs have a limited life span when it comes to read/write cycles (like Flash memory) so defragging one would use quite of read/write cycles. And since SSDs use something called “wear leveling” to mitigate the read/write cycle lifetime (it writes across the memory area that’s less used) anytime you write to the disk it will become fragmented, regardless of if there is free contiguous space.

No, it should not. I’ve been reading about SSDs a lot lately since I’m getting a Windows 7 laptop with an SSD. Windows 7 is optimized for SSDs, meaning that it performs differently and automatically disables things like defragmentation when an SSD is being used. In Windows Vista and earlier versions, you’ll have to disable it yourself. Defragmention can shorten the lifespan of an SSD.

Definitely do NOT. Fragmentation actually is the best way to get performance out of an SSD; there is no penalty from reading from a different section of the drive since there is no mechanical head to wait on and many drives allow multiple pieces to be read at the same instant if they are fragmented onto different flash memory chips—if they were all on one chip you would have to read the data out serially instead of in parallel. Also, moving data around so it’s contiguous just wears out the drive and shortens its life. The only thing you’ll want to do is TRIM the drive if your drive and operating system support it.

I’ve actually written up a blog post on some of the technical tidbits about SSDs (I hope that doesn’t seem self-promotional).

@timtrueman No, not at all. Great blog post!

I would not worry so much about the life of a modern SSD as I have seen the math and it has been calculated at 51 years of solid read/write cycles 24/7 at the 80MB/sec. Okay, SATA is about twice that fast, but I think that 25 years is more than long enough. Oh, wait…. many drives do not spend their entire lives doing nothing but read/write cycles, s they will exceed those rather generous lifespans.

However, it is rather pointless to defrag an SSD anyways, partly due to the very minimal speed gains that you might not even get, and partly since normal wear-leveling will refrag it quite quickly and wipe out those minuscule gains if you get them in the first place.

@jerv How new is modern for an SSD? I’m still not in the market for one (still too small and expensive for me) but it would be handy to know if I suddenly change my mind and decide to get one.

I think what worries me more about SSDs than the lifetime is the performance hit that’s supposed to happen with the re-write cycles.

@mrentropy Basically anything from the last five years is definitely safe. That link I posted is actually a little dated and things have improved since then.