Is writing to a compressed NTFS filesystem OK?

[PaulBx1]

I was reading ICPUG's Lin & Win project, and somewhere in there he comments that Puppy can handle writing an uncompressed ntfs, but not a compressed one. Is that old, no longer valid info, or still the case? If the latter, shouldn't such file systems be mounted ro rather than rw?

[Flash]

I never heard of a compressed NTFS filesystem. Can you give us any more info on it? Links?

[amigo]

Yes, windows can use compressed ntfs or fat partitions -but it is very risky. If the fs gets corrupted windows can no longer boot. Linux fs drivers do not support either type of compressed win filesystem and I'm quite sure they never will.

[PaulBx1]

Flash, just go to the c: drive in windows explorer and click on properties. There is a check box for compressing the drive, which is checked on my netbook with a small solid state drive.

When Puppy mounts this drive it probably ought to mount it "ro", so this looks like a bug to me if ntfs-3g (or whatever it is) cannot handle compression. Writing such a drive from Puppy will probably kill the windows install. I'm not going to try it to check, however.

[amigo]

No bug. Neither ntfs-3g nor the in-kernel ntfs driver pretend to support compressed windows filesystems.

[Makoto]

Yeah, this is the first I've heard of compressed NTFS, as well. Is it supposed to be another drive-stacking method, like MS' earlier DriveSpace/DoubleSpace methods? Just curious.

(I probably wouldn't want anything to do with it on my XP and Vista systems, anyway... the less I screw with the filesystem, the better. )

[gcmartin]

Have been using this for years on MS servers. Works fine in Windows. Able to run defrag when necessary and all MS tools work with the files on the compressed partition. Usually you can get at least a 2X compression ratio. And, more. Also, I have never experienced any negative MS issues in using these partitions. You can freely back them up as well as restore them without any hints of data problems.

If one decides to use this facility, I advise to ONLY do it for data; not for system files. Systems files are accessed much more frequently tnan your data files. Thus you gain much drive space without sacrificing system performance.

From a Linux perspective,I am not aware, nor have I ever tried to read/write to any compressed Microsoft partition from Linux.
Thus, I would use caution when attempting to manage ANY data on an NTFS partition...even if Linux mounted it for you. And most certainly, I would be cautious in writing any data to the compressed partitions.

Again, I MUST admit, again, that I have never attempted data management on any compressed NTFS partition under LInux.

[PaulBx1]

No bug. Neither ntfs-3g nor the in-kernel ntfs driver pretend to support compressed windows filesystems.

I don't know what this means, "pretend to work". Does it mean ntfs-3g refuses to write to such a partition even though it has been mounted "rw"? Or does it mean the driver writers didn't support it, and will attempt to write it as if the partition is not compressed? Thus trashing the file system?

If the latter, I call that a bug. It should be mounted "ro", if it is mounted at all. Better yet, ntfs-3g should refuse to mount it, saying why.

It may be that the file system is just ordinary ntfs, and only individual files within it are compressed. I believe one has the option to compress individual files.

[gcmartin]

Easy enough to check and report back here.

1. Create a small partition, say 1GB
2. In Windows - format & compress the partition and add some files
   1. Boot MS and format the partition NTFS
   2. MS will assign it a drive letter.
   3. Open explorer and right click the drive letter of the 1GB drive
   4. Select the option to compress
   5. Copy a couple of files to the drive letter
   6. Copy a video to the drive letter
   7. copy a music to the drive letter
   8. Shutdown MS normally
3. In Puppy - See if you can read and write to the partition
   1. Boot a current Puppy
   2. Click the 1GB drive's icon on the desktop
   3. Play the music file
   4. Play the video file
   5. See if Puppy will create a text file on the drive
   6. Shutdown Puppy
4. In Windows
   1. Boot Windows
   2. Can you see and edit the text file you created?

let us know how this turns out.

Estimated time to accomplish this - 15-20 minutes.

[amigo]

I meant that there is no intention, claim or pretension to support MS compressed filesystems. It's not a bug because they tell you that compressed FS are not supported and should not be used by their NTFS/FAT drivers.