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Don't defrag your SSDs or your USB thumb drives. Reformat them appropriately if you need to.

In a recent newsletter, you say that SSD drives should not be defragged. What about flash or thumb drives? Also, can (or should) they be reformatted? I'm using Windows 7.

In this excerpt from Answercast #69, I look at drives with flash memory (USB, SSD, etc.) and why they should not be defragged.

Defragging SSD drives

SSD drives and flash drives should not be defragged. Period.

They are both based on the same technology: it's the quality of the technology underlying that is the quantitative difference between the two. SSD drives use flash memory - it's just a higher quality that lasts longer.

Movement of physical disk head

Regardless, defragging flash drives, defragging SSDs typically has very little impact on performance because defragging is all about dealing with physical head movement in a traditional hard drive - and there is no physical head to move in an SSD or a flash or USB thumb drive.

So as far as I'm concerned, don't defrag anything that's based on flash memory; be it an SSD or USB thumb drive.

Reformatting flash memory

Reformatting, sure. Reformat it if you need to.

My tendency is to reformat it using a quick reformat; which actually only overwrites the root directory marking the entire drive as "empty and available for use" and actually involves very little writing. There's no reason not to do that. It's simply, like I said, a quick way to erase the entire thing and set up a new file system, a new clean file system.

Now, the question becomes do you ever need to do a full format? In other words, rather than a quick format (which just updates the root directory on the drive), do you ever need to do a full format that actually overwrites all of the sectors on the device?

So, my thinking is that in general, you do not. However, if you are concerned about the data on the drive potentially ever being recovered or undeleted, then yes, a full format is called for. It will overwrite every sector on the drive exactly once, which is enough to render everything on a flash drive practically unrecoverable.

So, those are the two solutions I'd go for. Don't defrag your SSDs or your USB thumb drives. Reformat them appropriately if you need to.

Article C6015 - November 11, 2012 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Tom R.
November 13, 2012 8:53 AM

What about secure file/free space wiping on a flash or SSD drive? Is it potentially harmful?

November 13, 2012 8:53 AM

"Don't defrag your SSDs or your USB thumb drives." Oops, I have defragged a thumb drive and I never thought anything about it. Have I messed it up or shortened it's life? So far I haven't noticed anything wrong with it, but I only use it for document storage.

You may have shortened its life, but if, or by how much is impossible to say. As always, make sure what's on it is backed up elsewhere.

Mark J
November 13, 2012 12:41 PM

If you do a free space or secure wipe, be sure it is set to only overwrite once. Once is enough. Anything more is contributing to wearing out the drive.

Vanya Marin
November 13, 2012 4:37 PM

I don't wanna sound spooky nor paranoid, after all - I don't care, cause I have nothing to hide - but... Regarding those full formats for security reason, which long time ago proved to be insufficient, and people always advice you to overwrite your disk or USBmemory with new data and that only then your old info is gone....
Well, I was "honored" to witness how much more further this 'digging' into your old data has gone.
Friend of mine worked for renown state agency as survailance team IT-guy. Left that place, started new job with knowledge he picked up there. Now he owns company for RECOVERING LOST DATA from old, broken, burned, dead hard disks... It is more sience lab than a "office" - however - I had an accident with my HDD few months ago - it fell from the table and actuator broke...
I took it to RECOVERY LAB and was truley shocked when I figured that they have retrived back 3 last overwrites from same part of disk..
They saved music, but also a movie that was there before (I overwrote movie with music) and one "overwrite-layer" before that - there were pics, pdf and doc files... All from same part on the hdd plate - got it all back - very confusing looking, though - every file is withn 10 folders and subfolders with ridiculous names made of zillion numbers... So it lasts a while untill you find what you're looking for, cause it isn't 'folder tree' and file names as they were on your disk...
However, I just figured that obviously, if you really want your data gone - you simply need to chopp this thing down to small pieces...
Or just don't have secrets you need to hide badly :)

Flash memory is different technology than magnetic hard disk platters, and does not suffer from this scenario.

November 13, 2012 7:06 PM

If you felt the need to make sure your thumb drive was empty and were concerned about someone recovering your data, wouldn't a hammer be a simpler option?

Vanya M.
November 14, 2012 6:53 PM

Hey James - my point exactly - hammer is the only safe solution (that is what I ment wne wrote to "chop it down to small pieces" - sorry about my English - luckily you have put right words for my thoughts here)

Joe F
November 16, 2012 5:09 AM

Sometimes a full format is called for if you're getting disk errors (read/write, etc.). As flash memory wears out, some sectors are no longer reliable and a full format will remove them from service and restore the drive to "like new" performance (minus a few sectors).

November 16, 2012 9:37 AM

My suggestion for wiping a drive. Is just Encrytp the whole Drive. Than wipe only the free space and than do long format. I really think this this is about the easiest and fastest way to render the drives contents unreadable. Please offer your thoughts to this menthod.

That sounds like a lot of unnecessary writing to a flash drive. A single full format or a delete followed by a simple wipe of free space should be enough.
November 17, 2012 7:31 PM

I have YUMI on a Flash drive with several LIVE OS ISO images. I have to defrag it when I update an ISO because ISOs have to be one continuous chunk of memory for YUMI to launch them.

Mark J
November 18, 2012 1:17 AM

The safe way to defrag a flash drive would to erase everything on it, and then copy the file or files onto it. When there are no files on it, everything would be saved on it in sequence.

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