Persistent Home, will my existing windows partition be safe?

Quote:

---

Not really true. There are three totally different NTFS drivers for Linux. The 2.4 kernel has a crappy and limited driver and the 2.6 has a much more advanced one but there is a backport to 2.4 as well. Write is completely disabled in 2.4 and Knoppix doesn't use the advanced driver's backport. The advanced driver supports read-write persistent homes SAFELY for over two years now. Several other distros have this feature for a long time. The first one was Phat Linux in 2002, running Linux fully read-write from NTFS. Corrently the most popular such distro is TopologiLinux but there are more

---

So are you saying that when I boot I could type knoppix 26 tohd=/dev/hda2 (hda2 is my NTSF) and I could install and run knoppix from my ntsf partition without screwing up my windows and being able to read/write? Or does that just apply to other versions of linux, if so, could I get some links? Thanks.

(This is where I wish we could get definitive answers from someone like Fabian, or Klaus Knopper himself -- the people who wrote the scripts that make Knoppix run.)

Garibaldi, first off, when you use "tohd"/"fromhd" and "bootfrom", Knoppix runs from a read-only image. It's just like running off the CD, except faster. It's not read-write.

The difference between "fromhd" and "bootfrom" is that "fromhd" uses the ~700MB /KNOPPIX/KNOPPIX file from the CD, while "bootfrom" uses the entire ISO image.

In my experience, Knoppix is written so it won't install using "tohd" or run using "fromhd" (the flip side of "tohd") with an NTFS partition. I'm not that good at bash scripting, but it looks to me like the "linuxrc" script in "minirt26.gz" checks the partition type, and simply won't allow you to do it unless your partition is ext2, ext3, vfat, or reiserfs.

You can use "bootfrom" and boot the ISO image from an NTFS partition, but again it's as read-only as running off a CD.

So the short answer would be, no.

Someone in Japan has recently modified Knoppix 3.4 to run a "fromhd"-like poor man's install off an NTFS partition -- see this thread for the download link. There's an installer included that installs "GRUB for Windows" (looks a lot like the one from Topologilinux), that loads after NT Loader. It's still read-only, though.

I've used Topologilinux (http://www.topologilinux.com), and it's very good. It creates a couple of large files on your NTFS drive -- one for swap and one for the actual installation -- and allows you read/write access within those files. No partitioning necessary.

You just have to be careful to mark them "don't touch me" when you defrag!

I don't know technical details of how Topologilinux does its magic or understand how Linux NTFS drivers work. AFAIK, Irgu is correct in saying that Linux has tools to allow you to resize NTFS partitions safely, as well as to safely write within files that already exist on the partition. But from what I hear, creating and deleting files on an NTFS partition using Linux is still not recommended.

Quote:

---

Originally Posted by eco2geek

(This is where I wish we could get definitive answers from someone like Fabian, or Klaus Knopper himself -- the people who wrote the scripts that make Knoppix run.)

---

Based on Klaus comments on the devel list and forums, apparently he confuses or not enough interested in the several NTFS driver status (crappy NTFS driver, new NTFS driver, Captive NTFS, user space utilities, etc) thus he took a defensive strategy using the default driver from the kernel. In case of 2.4 this is the crappy one (also you can't use it for home) and the better one in 2.6 (you could use it for home). And optionally you can also install Captive NTFS. I don't know Fabian's opinion.

To make things more complicated, the 2.6 kerne'sl geometry detection code and Parted has a serious bug. When you repartition a disk then it can make Windows unbootable. QTParted uses Parted and when it's run on 2.6 kernels it can cause this problem with both FAT and NTFS. However since today at least 80% of the Windows computers use NTFS (or all new Windows installs basically) thus people report QTParted on 2.6 kernels trashed Windows NTFS. They make and spread the wrong conclusion NTFS is still unreliable altough the problem now is really Parted. Luckily Parted was fixed recently.

Quote:

---

Originally Posted by eco2geek

You just have to be careful to mark them "don't touch me" when you defrag!

---

Why? It shouldn't matter. Any pointer?

Quote:

---

Originally Posted by eco2geek

I don't know technical details of how Topologilinux does its magic or understand how Linux NTFS drivers work.

---

It mounts NTFS read-write then loopback read-write mount the large "container" files for Linux root fileystem and swap from the NTFS partition. Basically what the NTFS driver does is only overwriting these files what is safe. At an upper layer this is seen as reading and writing everywhere.

This is also the reason why defragmentation shouldn't matter because the Linux NTFS driver will find the part of the files anywhere, no matter where the defragmenter relocates them.

Quote:

---

Originally Posted by eco2geek

AFAIK, Irgu is correct in saying that Linux has tools to allow you to resize NTFS partitions safely, as well as to safely write within files that already exist on the partition. But from what I hear, creating and deleting files on an NTFS partition using Linux is still not recommended.

---

You can't create or delete files (since W2K and up). This functionality was disabled in the crappy driver about 3 years ago and neither is implemented in the new driver yet. So basically you can recommend to create or delete files because it's impossible, no driver code will run at all, only the "permission denied" message part.

However you can use Captive NTFS to create and delete files but it has its own problems, like legal, slow, complicated, only certain XP drivers work, it doesn't work with 2.6 kernels, can trash NTFS if it's not umounted properly or otherwise, 100 MB file size limitations, etc.

Quote:

---

Originally Posted by Irgu

Why? It shouldn't matter. Any pointer?

---

No. I guess that was just my assumption at the time. Scratch that. (If you use Topologilinux's "GRUB for Windows" -- I use it to boot Knoppix -- you do have to reinstall it when you defrag, but that's not the same thing.)

Quote:

---

Originally Posted by Irgu

You can't create or delete files (since W2K and up). This functionality was disabled in the crappy driver about 3 years ago and neither is implemented in the new driver yet. So basically you can recommend to create or delete files because it's impossible, no driver code will run at all, only the "permission denied" message part.

---

Interesting. My question is, how come the Linux kernel developers were able to implement vfat so well, but not NTFS? Is vfat just better documented, or is NTFS harder to "reverse engineer," or...?

Quote:

---

Originally Posted by Irgu

However you can use Captive NTFS to create and delete files but it has its own problems, like legal, slow, complicated, only certain XP drivers work, it doesn't work with 2.6 kernels, can trash NTFS if it's not umounted properly or otherwise, 100 MB file size limitations, etc.

---

Also very interesting. Didn't know that Captive didn't work with kernel 2.6 or had 100MB file limitations.

Quote:

---

Originally Posted by eco2geek

My question is, how come the Linux kernel developers were able to implement vfat so well, but not NTFS? Is vfat just better documented, or is NTFS harder to "reverse engineer," or...?

---

NTFS is much, much more complex than FAT, for example see http://www.ntfs.com/ntfs_vs_fat.htm

From the above table it also turns out that NTFS supports features that the main Linux filesystems usually don't (e.g. compression, encryption, streams, unicode).

There are many Linux filesystem developers, furthermore several companies support Linux native filesystems development (IBM, Red Hat, SUSE, SGI, Namesys, etc) by employing many developers (some over 10, just to work on Linux filesystems!). But NTFS is developed by only a couple of guys in their spare time. Hence the development is quite slow, if nothing would happen.