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Back in the 90s, my home computer was an Acorn Archimedes. It had on it a piece of software called ArcFS, which allowed you to create compressed archives, a bit like zip files.

Unlike zip files, they could be mounted as a disk, a bit like dmg files on a Mac.

Unlike dmg files, they were compressed and writable.

If we could do this in the 90s, why can't we do this now? Today I use a Mac, and while I can create compressed disk images, they are not writable. Conversely, writable disk images are not compressed.

What is today's equivalent of ArcFS, and why isn't it more common?

David
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5 Answers5

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I'm not sure which ones are available for Mac OS -- but there are still a lot of r/w compressed filesystems around:

  • e2compr being a kernel-patch for EXT2
  • Fuse offers a list of compressed filesystems, including such with r/w support like e.g. compFUSEd and LZOlayer_fs
  • Solid File Sysem is multi-platform (explicitly states support for Mac OS X) and supports encryption as well as compression

So it is still possible, and is still done. Why it is not more widely known, I cannot tell...

kubanczyk
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Izzy
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You don't say what version of Mac OS you are using but Mac's DO support compression natively - at least it has from Snow Leopard (10.6) onward. It's called "HFS+ compression".

For reference, there are several compressed file system for Linux and @kinokijuf has already mentioned NTFS compression.

So the world of compressed filing systems is still alive and well - it's just that, on Mac and Windows at least, it is now an embedded feature of the native disk formats.

Julian Knight
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7

Windows NT has supported compression of individual files on NTFS volumes since version 3.51.

kinokijuf
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5

Two recent file systems, ZFS and btrfs allow to enable compression on read/write file systems. The file systems can be stored on disk files and mounted as such.

There is at least one open source project to support ZFS on MAC OS/X and also a commercial solution.

jlliagre
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The other answers already point out that compressed FS still exist. As to why they are no longer popular - the main reasons are probably:

  • Disk space is quite cheap nowadays - many people I know never manage to fill their disks
  • Even if you run out of disk space on your main HDD, external storage is now much more practical to use. 20 years ago, all you had were tape and diskettes - now there are external harddrives, SSDs, big USB sticks, DVD-R/RW, which are both simple to use, reasonably fast, cheap and have high capacity.
  • If you do manage to fill up a disk, it is usually with audio/video data (music, photos, movies). These are usually already stored in compressed formats, so a compressed FS would not help.

Actually, I think the last point is the main reason.

sleske
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