Copying/moving compressed folders between drives without decompressing

[Rephlexion]

Hi there, I was hoping there might be a way to move a compressed folder from one drive to another without having it decompress and require decompression again. I'm getting amazing results when compressing directly on a gen 4 m.2 drive, and decent speeds when compressing directly on an old HDD -- much faster than standard Windows NTFS compression flagged folders, but it still feels like a bit of a waste to have to both copy AND recompress on a slower drive (especially when I can get more than 50% compression on some things, and could save time transferring less data!)

It certainly didn't work any better with copying between standard Windows NTFS compression flagged folders, and I came looking for CompactGUI after I got tired of all those 50 MB/s standard compression writes, even to m.2 drives that can do 3-7 GB/s. I'd like to do the compression work directly on my fast drive, then copy the compressed folders to slower drives like HDDs, SD cards, maybe even some ancient USB drives where a little less data to move would go a long way! Maybe this is a fundamental issue with NTFS compression and just isn't possible? Either way, CompactGUI is already saving me a ton of space AND time, so thanks!

[Iridium-IO]

You can't do it, because of how Windows handles WOF compression. Instead of copying the data in the file to a new location (like when you make a standard .zip archive), it does the compression in place, and marks the new data as a sparse file - that is, to anything except the WOF driver, it appears to be a totally blank space on the disk. Even the flags identifying it as compressed data don't really exist at a higher level, so any attempts to read or write the data have to pass through the WOF driver. All of this might sound painful, but it's actually how Windows abstracts away the fact that the files are compressed, so that no other programs need to care about it being compressed or not. They just see the file they need.

The downside is, when you try to copy a compressed file, it still has to be seen exactly as it should be in order to not break everything. That means it needs to be uncompressed on the fly and then rewritten to the new disk.

Have a look at the explanation here, it'll give you a better idea of it.