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I have a hard drive with Windows XP SP3 installed on it. When the drive is connected through the standard SATA connector inside the laptop, everything works as expected.

However when I remove the drive from the laptop and connect the drive to the external USB adapter, almost all files / folders lose the 'Owner' field contents. I was wondering why could that be. I've tried two USB adapters and this happens on each. I could take the ownership of all of the files, but this would overwrite the Owner value (the Owner value that is present when the drive is accessed through standard SATA connector in the laptop).

//edit: if the hard drive is used through the USB adapter, I can't access most of the files, at least until I take ownership of the files (/folders).

This is how it looks like:

HDD inside USB adapter: enter image description here

HDD inside laptop: enter image description here

(note the Owner column)

//edit: some of the files on the first screenshot have Owner field filled up. That's because I took the ownership of those files / folders to be able to access the files on the hard drive.

//edit2: also, if the hard drive is connected through USB adapter and if I've took the ownership of some files by the 'ddd' user, then if i login as a different user (lets say 'eee' user), the owner field is _still_ empty:

ddd user: enter image description here eee user: enter image description here eee user can't access the 'ddd' folder.

Both users have Administrator priviledges.

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1 Answer 1

When you create or edit a file on a NTFS drive it gets the user or group assigned to it. Microsoft explains this mechanism pretty good. Basically every file gets a domain group and a user assigned. (DOMAIN\user)

Of course they don't really talk about how it works in depth but the folks who rebuild ntfs-3g for linux had to dig into the filesystem to understand how it works. There is an article that explains how linux users can be mapped to the windows users for easier workflow. Although we are not talking about linux here, the information you can see is that the mappings are a set of different numbers, eg:

500::S-1-5-21-1833069642-4243175381-1340018762-1008

The part in front of the colons is the linux user ID, the part after that is the Windows User ID, which is actually stored in the owner field. Although Windows of course does not need a linux user ID it will have a similar mapping table, mapping the systems users against the IDs stored in the file.

When you are looking at a file now on the correct system that actually has this owner, Windows can read and identify this ID. But if you take the drive to another computer it can't be mapped, simply because the files owner is not known to the other system.

(I am only guessing here, but to me this seems to be the reason)

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