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I use NTFS compression on some folders, I understand the pros and cons of this, but for my use case it is preferred.

I have noticed some odd behavior for many years. Some applications do not "honor" the directory compression flag.

I have never been able to determine why this is so. I'd like to understand the reasons and if there is any way to "force" and application to honor it.

Currently I just use a batch that runs compact from time to time on the required folders.

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up vote 6 down vote accepted

Do you mean that the compression checkbox is unchecked altogether?

Probably what's happening is that those applications are creating files somewhere else then moving them into the destination folder. A move on the same partition won't force the compression to be applied because of the new parent.

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You were right. The move is what was causing it. Much of the time it is a move from the %TMP% directory. – Wayne Arthurton Mar 12 '11 at 20:09
A move also won’t respect the permissions. – kinokijuf Feb 12 '12 at 19:27
@kinokijuf: Only on XP. Vista and 7 apply permissions of the target on moves now. – afrazier Feb 12 '12 at 21:02
@afrazier Only if you have „easy file sharing”. The filesystem hasn’t changed at all. – kinokijuf Feb 13 '12 at 12:36

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