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Windows 7/Trying to understand defragging


Hiya Scott

Until recently I was happy to rely on Windows' own defragging facilities and if it said a drive didn't need it I accepted that. However I recently started using Defraggler and that told an entirely different story.

I'm concerned about one drive in particular. It's quite a large volume (about 2.3tb) of a 3tb drive and is about two-thirds full and defragging it takes quite a time (as you can imagine). I've no problem keeping the computer on while it does its job and when it shows it's almost finished I take the opportunity of rebooting the comp to complete a long-awaited procedure with the intention of completing the defrag on starting it again.

My confusion is when I start defragging it again it's gone from almost finishing to 6% defragged taking yet another day or two to finish and I don't understand this discrepancy.

If you reckon it's just the way it works or just an indication of the state of the volume, I'd be happy with that, just as long it isn't a sign of anything bad happening to the drive. I'd have no problem replacing the entire drive but I'd rather not if it isn't necessary. Defraggler does say the condition of the drive is GOOD but can I rely on that?

Can you help me understand this discrepancy please?

If it's important I'm running Win7 32-bit

Thanks very much.

HI there

Defraggler is better than the standard windows Defrag, but the windows version will still serve you ok.

When defragging the PC wont be able to defrag files that are in use at that time, pagefile and other programs loaded into memory.  when you reboot this may change things so it has to recalc and start again.

In terms of the drive being healthy defragging programs aren't the best to tell you this, also the windows drive management snap in has told me a drive was healthy when it wasn't, many times!

To check a drives health you need a program that can examine the raw S.M.A.R.T. data on the drive, I use Drive Sentinel which you can download a free version. Its great because it keeps a history of your S.M.A.R.T. data and can therefore show trends in write speeds and errors occurring.  Another program that will give you a snap shot of the S.M.A.R.T. data is Crystaldiskinfo, but this doesn't store a history, this is totally free.

Hope this helps


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scott bartholomew


General trouble shooting Hardware issues Networking issues I am not a software developer,but I can do some basic scripting in DOS and BASH.


Worked in IT for over 10 years and currently provide software and hardware support for a very large network of computers, including servers.


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