I’d forgotten about NTFS compression. This thorough review, Thrilling tales of NTFS compression, reminded me that it’s a reliable tool for a few circumstances: (Quotes are from the Dans Data link):
- Laptop short of space: “Program Files contains a lot of stuff that's read moderately often but not written to very much, which is a good access profile for compression to have no perceptible speed impact at all, after the half-hour or whatever you'll be waiting for everything in a typical large-ish Program Files, on a laptop with a slow-ish CPU, to be compressed…
… You can't expect a terribly large amount of compression from this, but when I tried it, I turned a 35.4Gb Program Files into a 27.6Gb one - 78% of its previous size, and a perfectly worthwhile 7.8Gb saved…”
- Microsoft Access databases (however this may impact I/O slightly). These compress extremely well.
- Windows BMPs – though almost no-one would keep these around outside of (gasp) screen shots pasted into PowerPoint.
Practically speaking, I think NTFS compression is most useful if you have to carry around a lot of large Microsoft Access databases on a laptop (consider using NTFS on a directory) or if you need to free up a few GBs on any laptop.
NTFS compression is not compatible with NTFS encryption (which most people will want to avoid, see the linked DD article). I don’t know if it’s compatible with other encryption schemes corporations apply to hard drives these days.
I think the closest OS X equivalent would be the 10.5 expandable sparse images.