I had an external drive, which I decided to defrag. Defraggler would not work on the external drive, a USB drive connected to my computer, which is a laptop. So, I went looking for a way to defrag my external drive and found your site. Someone had asked that question, and I followed your instructions to right-click the drive and select defrag from the menu, and Windows defrag would defrag the drive. The external drive had only 10% of the drive’s size in data, but if I remember right, defrag does not distinguish between data and empty portions of a hard drive.
I set defrag to work using another 3rd party program called “No Sleep”, which simulates a person moving the cursor, so the computer doesn’t shut down. Then I went to bed. When I awoke the computer was hung up, and I had to back out of defrag. When I looked at my external drive almost all of the data was gone.
The external drive was a backup of sorts, and it was not itself backed up. I hadn’t gotten around to that. So, hundreds of hours of work was lost. I started by going back on the web and found an article that warned that Windows defrag often hangs up on large drives. My external drive was a terabyte in size. The lack of warning for this on your site led to the loss of my data.
I have 8 recovery programs, all third party, which I rarely use. Six of them could not recover anything. The seventh recovered everything. So, I’m whole. But you need to add a warning in your instructions to warn people that Windows defrag has problems with large drives … and maybe small ones. I never have used Windows defrag since I was alerted to the existence of third party programs that do a better job of defragging.
I’m sorry you had such a time of it, and I’m very relieved you were able to recover your data.
Unfortunately, there’s really no warning for me to add, other than what I already repeat ad nauseum: if there’s only one copy, it’s not backed up. Your data was already at risk: the drive could have failed at any point and it would all be gone.
In fact, I suspect that something like that was bound to happen. Defragging a drive should never cause data loss, unless there’s a pre-existing underlying problem.
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Defragging should work
Both Windows’ own defragging tool, as well as the third-party tool Defraggler, should have worked on your external drive.
That Defragler couldn’t see the drive at all leads me to believe there was already a problem with the drive or the USB interface to it. If Windows could see it, then Defraggler should’ve been able to see it.
Further, Microsoft’s own defrag should have worked without incident.
I have defragged large external disks without incident many times, and there’s nothing about your situation that leads me to believe that it shouldn’t have worked.
A defrag can cause data loss if….
What I strongly suspect is that something else caused Defraggler to fail to work for you and ultimately caused the data loss you describe.
Perhaps a hardware issue; perhaps the USB interface on the drive; perhaps the drive itself – there’s no real way to know.
For all I know, it could even have been due to this “No Sleep” program you’ve mentioned that I’ve never heard of. (Though, assuming it’s as simple as it claims to be, and is not malware itself, it’s unlikely it would be a problem.)
But, yes, defragging is a disk-intensive operation, meaning it drives the hard disk heavily. It makes sense that hardware failures or other marginal issues would be more likely to appear when the disk is under the stress of heavy use.
There’s a bigger problem
Here’s what I see as an even bigger problem.
The fact that you were facing data loss at all if this drive failed means to me that the data was not backed up – it existed ONLY on the drive in question.
That’s a recipe for disaster.
I’m sure you’re aware that drives can fail – catastrophically – without warning, regardless of what you happen to be doing with or to it. It doesn’t have to be a defrag, or a chkdsk, or any other kind of heavy use. Drives fail for a variety of reasons, occasionally without warning or odd behavior at all.
And sometimes, when they die, they die hard, destroying all the data that they contain.
You were very fortunate to recover your data at all.
My recommendation to avoid data loss
My very strong recommendation is my most basic, and my most frequent: make sure you’re backing up. Don’t put it off. Automate it if you can, so you’re not the weakest link in the chain.
Think about your hard drive suddenly and permanently disappearing. Would you lose anything you cared about? That’s the data-loss litmus test. If the answer is “yes”, you’re not sufficiently backed up.
Then, only after everything is backed up, I would run CHKDSK /R to scan the surface for errors, as well as check the file system for issues. If Defraggler still doesn’t see the drive, then there’s an issue that, in my opinion, needs to get resolved before I’d feel good about using that drive at all.
I’d also consider turning sleep mode off completely, so you don’t have to rely on yet another tool to keep the machine awake. (I could be wrong, but I believe the defragging will prevent sleep anyway.) I’ve experienced too many issues with sleep on various computers to trust that it’s not part of the problem.
P.S.: One clarification
You mentioned, “…if I remember right, defrag does not distinguish between data and empty portions of a hard drive”. That’s incorrect. Defragging is only about the actual data on a hard drive, and doesn’t care about (or specifically operate on) free space.
In fact, one way to completely defrag a non-system drive is to:
- Copy the contents of the drive elsewhere.
- Erase everything on the drive.
- Copy the contents of the drive back.
Of course, this assumes you have room somewhere to copy the data to. The process of copying the files back, as long as it happens sequentially (one file after the other), puts them “in order”, which is the ultimate goal of a defrag operation.