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C drive does not appear in Disk Defragmenter?

by spursfan2110 / August 2, 2010 1:33 AM PDT

I was going to get around to defragging my C: drive today, (which I don't actually remember if I've ever done in Windows 7) and when I opened the Disk Defragmenter, the C: drive doesn't show up, and as a result I can't defrag it. Any ideas as to why this is? I have an HP Probook 4510s, if that helps.

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Is there a C drive?
by R. Proffitt Forum moderator / August 2, 2010 2:44 AM PDT
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There's definitely a C: drive :)
by spursfan2110 / August 2, 2010 1:59 PM PDT
In reply to: Is there a C drive?

I definitely have a C: drive. I'm running the Windows 7 Ultimate Edition, 32 bit. My laptop is about a year old and came with Windows XP, but I upgraded to this version of Windows 7 around December. I can access my C: drive fine otherwise, saving documents, reading from, etc. It just doesn't show up in the Disk Defragmenter. My USB drive and External Hard Drive both do show up, and I find it odd that they do and the hard drive my computer came with doesn't. It's a pretty simple problem in terms of the symptoms.

Sorry, I'm new here, what other details would be helpful?

Here's a screenshot;

In the picture, in Explorer there are obviously 5 drives. C: hard disk, D: which is some HP thing that has been on my laptop since I got it, an H: drive which is my external Seagate Hard Drive, E: DVD drive (equipped with Starcraft!) and a virtual G: disk drive, but of the Hard Disk Drives (C, D, and H) only D and H show up in the Defragmenter (as can be seen in the windows on the bottom right of the posted picture).

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by MarkFlax Forum moderator / August 2, 2010 8:27 PM PDT

I thought I had been clever and found the answer. It turns out I may only manage to confuse the issue. But anyway, here is what I found;

I Googled, Windows 7, "Only disks that can be defragmented are shown"

Only 3 hits, and only one of those an English language link, the other two are foreign language;

If C was an SSD, (Solid State Drive), it seems Windows 7 should automatically turn off defragmentation. But then I saw your HP_Tools drive which is some sort of recovery/tools drive, likely to be a separate partition off the primary drive. So if that is also part of the SSD then I am not sure why it is listed.

However the discussion in that link goes on to suggest that Disk Defragmenter was able to display the SSD.

Is your C drive an SSD?


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The link I shared
by R. Proffitt Forum moderator / August 2, 2010 10:49 PM PDT

May apply since you upgraded from XP to 7. I'd read that link one more time.

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Command line ?
by Bob__B / August 2, 2010 11:32 PM PDT

start>cmd>defrag c: /a

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Still no luck... :/
by spursfan2110 / August 3, 2010 5:48 AM PDT

Bob - Thank you, but I'm reluctant to edit the registry unless absolutely necessary because I'm relatively inexperienced in that area, but also, the link doesn't seem to be solving the same problem...that one seems to be a general data access problem which I have no issues with. Do you think that solution would still work though?

MarkFlax - Mine is definitely not a Solid State Drive, although what it said about Windows 7 auto-defragging was interesting...may look into that.

bob b - I've tried that, I get this:

Invoking analysis on (C:)... <--- This seems normal enough.

The dirty bit is set on this volume. (0x89000015) <--- Not so much.

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My thought is that
by R. Proffitt Forum moderator / August 3, 2010 7:11 AM PDT
In reply to: Still no luck... :/

You may never find a closer match. The issue has been seen a few times when there was an "upgrade" of the OS. Since there is so little to be gained or not much loss what fix this?

And if you really want to do this there's always Total Defrag from

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Makes sense
by spursfan2110 / August 3, 2010 8:54 AM PDT
In reply to: My thought is that

Ok, and thank you again for the input. Since I have very little experience editing the registry, would you mind taking one last look through there and verify that the instructions look good and shouldn't screw anything up? Thanks again Happy

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Why not skip the registry part?
by R. Proffitt Forum moderator / August 3, 2010 9:07 AM PDT
In reply to: Makes sense

Start at "Now start MMC" and see if you can get it done.

This sounds like an ownership issue.

-->> I didn't ask but should have. Is the account you use one that is an "admin"?

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Admin account
by spursfan2110 / August 3, 2010 10:35 AM PDT

Yes, it is.

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Idle thoughts
by Bob__B / August 4, 2010 7:12 AM PDT
In reply to: Admin account

If defrag is telling you the dirty bit is set that's normally a file system problem.

What happens if you......

Start>cmd> only test.

Start>cmd>chkdsk /f....file system test.

Start>cmd>chkdsk /r....partition test.

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Follow Up
by FortKnight / September 30, 2010 6:39 PM PDT
In reply to: Idle thoughts

Hello, I too recently encountered this same problem (C missing from Disk Defrag, running W7-64bit) and followed the flow of this thread in my own experimentation. Then I got to the part about "the dirty bit is set." I received this message as well and did some more follow up on it and learned that (at least in my non-tech savvy understand) it was suggesting that Windows needed to perform a scandisk on the hard drive. After allowing/encouraging this to happen on start-up, C reappeared in the Disk Defrag selection menu.

This may not help the original poster, who perhaps found another solution, but if anyone stumbles upon this thread as I did do try this simple step as it may save you some grief :).

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There is a fix
by defraginator / January 3, 2012 5:29 AM PST

Hello, the same thing recently happened on my computer. Somebody may have already said everything I am about to, but I hope this helps all the same.
Please do not quote me on this but i read that a "dirty bit" is where Windows flags one of your drives as somewhat corrupt, (Don't freak out!)or having some bad sectors as a result of not running a fragmentation as often as you should. This may also be caused by moving around a significant amount of files, as in installing a new operating system. The flag on that drive prevents you from running tools such as the defragmenter that may make the problem worse, if there is a problem. As I said before, I am not 100% positive about that explanation, but this solution worked for me. Just a few simple steps.
1. Open the start menu
2. Type in "cmd.exe" (with no quotes)
3. Right click the first result, and choose "run as administrator"
4. Type in "chkdsk/f" and hit enter
5. Wait until it says "c:\windows\system32" again then type in "shutdown/r" and hit enter. This will reboot your computer and hopefully the problem will be fixed! Hope I helped:)

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