Enabling RAM FS compression doesn't seem to compress anything

The RAM FS product looks impressive, it even seems to support NTFS junctions!

I had problem with other products when using RAM disks with exFAT before: the tools would use a junction in Temp folder and fail.

My only question here is that RAM FS did not seem to compress anything even after I enabled compression. Why?

Otherwise I absolutely love it and will install on all my computers!

We are very glad that you are happy with RAM FS. And yes, junctions/symlinks and reparse points are fully supported: RAM FS is a real file system rather than a disk emulated with exFAT on top, so the tools that break on exFAT temp folders should work fine with RAM FS.

Regarding compression, it is almost certainly working for you, but two things make it look like nothing happens:

1. Compression is a background, delayed process. Compressed is the resting state of the data, not something applied at write time. Freshly written data always stays uncompressed so that writes run at full RAM speed, and a background sweep packs it later, once it has gone quiet:

• the sweep wakes every 15 seconds;
• a 2 MB region must have been untouched for at least 60 seconds before it is considered;
• after a write thaws a region, that file is left alone for a further 5 minutes before it is re-visited.

This is a deliberate strategy to make sure that frequently-used data is not needlessly cycling through compressed and uncompressed states. So if you copy some files in and look straight away, you will see nothing compressed. Give it a couple of minutes of idle time and check again.

There is one case where it takes longer: files that are memory-mapped by an application (editors, indexers, database engines, antivirus scanners and installers all do this) cannot be compressed while the mapping is live, and Windows keeps the mapping around for a short while after the application closes it. Those files compress once that clears.

2. The volume's usage / free-space figures deliberately do not shrink. Volume space is accounted as if everything were uncompressed, so that a 16 GB volume always has room for 16 GB of data no matter what is stored in it. The benefit of compression is in the lower physical RAM use, not extra capacity.

The real figure is in the main RAM FS window: the Compression column shows the level, followed by the RAM actually reclaimed. Hovering over the cell shows the same as a tooltip. The memory bar along the bottom of the window also reflects the true physical footprint, so it drops as data is packed.


One more thing worth knowing: pre-compressed content (video, photos, ZIP/7z archives, installers) is detected per region on the first attempt and then skipped, so a volume holding only that kind of data will honestly show no saving. Compression is truly effective on compressible data like text, source code, logs, CSV and database files.
For a quick demonstration, you can copy a folder full of text files, source code or log files onto the volume, leave it for 2-3 minutes, and then check the Compression column.

I didn't realize RAM FS supported features like junctions, symlinks, and reparse points.

Is it possible to include a comprehensive list of all fully and partially supported capabilities to the user manual? It would be great for all RAM FS users to have such visibility into the full capabilities of the new file system.

Thanks in advance

Great idea! We've just added the Comparison with NTFS page. It covers what is similar between them, what RAM FS does better, and what is not implemented.

It also explains how free space is counted, as that does seem to cause some confusion: RAM FS doesn't store zeros, so the space reported as used is typically less (often much less) than the total size of the files on the volume.