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I have an external drive that I use between my work and two other laptops. Starting last friday (because I don't know if it is something I, or someone else did) on two of them, whenever I plug the external drive in, it just shows (in My Computer) NTFS below the drive, and doesn't give access to it.

On one of them, everytime I plug it in, it wants to to a "check disc for errors" after which it acts fine.

From what I gathered it has something to do with NTFS file permissions, but I cannot understand what I need to do to make those files on the external disc, including the external disc itself, accessible to everyone regardless of the operating system they're using and their user name data.

Does anyone know how to make the partition accessible to everyone, regardless of the operating system?

Answers to @fixer1234 questions from comments in the hope it will help diagnose the problem

Is it currently accessible to anyone (including via admin privileges) on the problem computers?
No. I am admin on one of those problem computers (my private one), and cannot access it. On the other one (my work computer) I am not admin.

All of the computers are running Win 7?
Yes, all computers are running Win7 32 bit with the exception of my work computer which is running 64 bit.

Does the same problem happen with any other external drive on the problem computers?
I only have this one, but the problem does not occur with regular USB sticks.

Anything the two problem computers have in common that the non-problem computer doesn't?

On the problem computers, did you try a live Linux session to see if you could access the drive?
No, sorry. Have no experience with Linux whatsoever.

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  • Is it currently accessible to anyone (including via admin privileges) on the problem computers? All of the computers are running Win 7? Does the same problem happen with any other external drive on the problem computers? Anything the two problem computers have in common that the non-problem computer doesn't? On the problem computers, did you try a live Linux session to see if you could access the drive?
    – fixer1234
    Jan 17, 2016 at 23:08
  • @fixer1234 - Thanks for trying to help. I've tried answering what I know in the edit.
    – Rook
    Jan 17, 2016 at 23:39
  • To rule out some unlikely software problem, see what happens if you boot in safe mode. I thought the Linux test might be a simple way to differentiate a hardware/HDD vs. OS problem (doesn't take any familiarity). Download the iso for a Linux distro (Mint Mate would be fine), and burn a DVD. Boot up on that into a live session (doesn't change anything on your computer). The desktop is pretty similar to Win XP or 7. Open the file manager. Plug in your external drive and see if it shows up. You should be able to see it and view its contents. If so, that would point to a Windows problem.
    – fixer1234
    Jan 18, 2016 at 0:05
  • You're focused on file permissions, but what gives you the idea that that is the problem in this case (e.g., an error message)? Lots of different kinds of problems can prevent access to a drive. Even when you see an error message, it can be misleading. There can be a different underlying problem and the first symptom it leads to produces an error message related to the symptom rather than the actual cause. Suggestion: diagnose the problem in a rigorous way, where you eliminate potential causes. Otherwise, you can get lost in the weeds of something that isn't the actual problem.
    – fixer1234
    Jan 18, 2016 at 19:58
  • @fixer1234 - I don't thin the problem has anything to do with file permissions. I'm not sure what is the problem - contacted our company's IT department today and they've also been unable to diagnose it. But until we find out what is wrong, I'm using the opportunity to learn more about file permissions and everything mentioned so far.
    – Rook
    Jan 18, 2016 at 21:54

1 Answer 1

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You might try changing the owner of the drive to "Users" or "Everyone", giving them Full permissions, and turning inheritance on.

To change ownership:

  1. To change ownership, right click on the drive in the computer where it works fine.
  2. Go to Properties
  3. Click on the "Security" tab
  4. Click Advanced near the bottom
  5. Click Change next to Owner at the top. If you don't have permission to do this you may need to click one of the buttons in the dialog box with the blue shield to open it with elevated permissions
  6. In the window that opens, type "Users" in the box and click Ok Check the box under owner to apply/replace on subcontainers and objects
  7. Click ok on each dialog box. You may get a window where it has a progress bar and is applying changes that may take a while depending on the amount of files

To change permissions

  1. Right click the drive, go to Properties, then Security, then Advanced--like above 2a. If you don't see Users in the lower list (like Users (ComputerName\Users) then click Add and "Select a principle" at the top. Type in "Users" into the window like you did with ownership 2b. If you do see Users, select it by clicking once and hit Edit 3a. Make sure Type drop down at the top is set to "Allow" 3b. Make sure Applies to drop down is set to "This folder, subfolders and files" 3c. Make sure "Full control" is checked. This should auto-check the other boxes when selected 3d. Click Ok
  2. Check "Replace all child object permissions entries with inheritable permission entries from this object" at the bottom of the window (you should be back at the one that lists owner at the top and the list of users/groups in the middle section)
  3. Hit ok. Like changing ownership, it may take a while to apply changes to all files

Try the drive on the other computers and see if you're still having issues.

Explanation

Windows/NTFS permissions are controlled using Access Control Lists (ACLs). All users and groups in Windows have a SID (security identifier). These look something like "S-1-5-32-545" for groups or longer for accounts. The ACL is a list of these and the permissions they have. My theory is the ACL was stating that certain accounts had access to the files while others didn't. Setting Users as the owner should have the same SID across all computers while a particular account will have a different SID on each computer even if the login name is the same (unless the computer is part of the domain like a work computer. The idea here is to also reset the permissions and change them to inheritable to new items will also have the permissions setup.

Usually a different operating system like Linux will ignore Windows permissions unless specifically configured to respect them. Linux typically uses bitmask permissions but things like SELinux can further complicate them. ACLs can also be used in Linux but I'm not sure what the requirements are to get those working correctly. It's also possible to map Windows users to Linux users but none of this pertains to this particular question--it's just for reference.

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  • I will try this. In the meantime, while waiting for answers here I found an article dealing with the problem lallouslab.net/2009/06/14/… and tried resetting permissions without taking ownership, as described in article. It took a while (hour or two), but to no avail. No difference. Should I try with "taking ownership"?
    – Rook
    Jan 18, 2016 at 8:07
  • It should be noted that I do not have backup of the drive in question, and although a relatively literal computer person, I have no idea what ownership and permissions entail - am aware of the terminology but never needed it up until two days ago.
    – Rook
    Jan 18, 2016 at 8:09
  • Permissions won't remove any files and if you're an administrator on the computer you should be able to change them regardless. You might also want to grant access to the Administrators group as well as Users because it's possible you might not be a member of both--which I didn't consider before
    – nijave
    Jan 18, 2016 at 19:21
  • arent administrators users too? I mean, doesnt giving Users access include Administrators as well?
    – Rook
    Jan 18, 2016 at 20:14
  • It appears maybe Administrators are implicitly members of the Users group although I didn't see anything looking online. This would make sense because Administrators should be able to override/change permissions of everything. I did a test on my computer and just granting Users access seemed to work fine
    – nijave
    Jan 20, 2016 at 2:24

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