File System

B.E · Post by **B.E** » Fri Mar 16, 2007 10:55 pm

I haven't been OS deving for over a year. during this time, I misplaced my OS code that I was working on. So basically have to start from scratch again. Anyway my boot loader now supports up to 2TB (using int 0x13 ah=0x41/42) with support for older bioses using int 13 ah=2. My native File system format was FAT. This time I want to implement a propper file system, like UFS.

I was just wondering if any of you know of any resources detailing the UFS format (e.g books, whitepapers.. etc), I know that UFS is based on FFS. If not, should I create my own.

Brynet-Inc · Post by **Brynet-Inc** » Sat Mar 17, 2007 5:55 am

I personally think there is a lot of confusion with UFS/FFS, OpenBSD uses FFS and FreeBSD's filesystem is UFS2.. But I think It's just an improvement of BSD FFS.

Even though the file system is completely BSD licenced, I can't find any extensive documentation on either OpenBSD's FFS or FreeBSD's UFS2.

Although:
http://en.wikipedia.org/wiki/Unix_File_ ... References

Has some docs circa ~1984, I'm guessing OpenBSD/NetBSD/FreeBSD have made changes since then.

You might be able to just study one of the systems implementations and write your own.. (Or just use one of theirs..)

Maybe someone who has some extra spare time can write up some detailed documentation on the File System (Because it really is great..)

Good luck

http://www.tldp.org/HOWTO/Filesystems-H ... tml#ss9.29
http://www.tldp.org/HOWTO/Filesystems-HOWTO-9.html#ffs
http://en.wikipedia.org/wiki/Unix_File_System

B.E · Post by **B.E** » Sat Mar 17, 2007 5:08 pm

Unfortunitly I'd already came across the links you had segested. but thanks anyway.

I did however do a google search last night for File system books that have information about UFS and came up with this which has 2 chapters on UFS1/2 and interestingly it also has chapters on FAT, NTFS, ext2/3.

File System Forensic Analysis

pcmattman · Post by **pcmattman** » Sat Mar 17, 2007 5:30 pm

I think FAT's problem is it's complexity and how fragmented it can become. I gave up on reading FAT drives simply because you can only have FAT12 on a floppy and that's the biggest piece of **** I've ever heard of. 12-bit entries in the FAT table put me off for life

.

The only thing that stops me from implementing something like ext2fs or whatever is the fact that I need to be able to access it from Windows

. Either that, or move my entire OSDevving across to my Linux system.

I actually have a book that teaches how to make an OS like UNIX but simpler (XINU) and it has information on I-block based filesystems. I'd recommend trying to find a book that outlines the BSD way of doing things (though that might be hard). Books are our friends!

carbonBased · Post by **carbonBased** » Sat Mar 17, 2007 6:27 pm

Unfortunately, I don't recall what the application was called, but I did once have a windows explorer-like application that would read linux ext2 file systems.

I recall searching for windows ext2 support apps, etc, some time back, and a found a couple solutions. They may still be in existence... might be worth a search if you're really interested in using this filesystem.

--Jeff

pcmattman · Post by **pcmattman** » Sat Mar 17, 2007 6:38 pm

I was about to download it the other day

. Then I wondered if it could write, and I figured, why waste a download? If it can write to the drive on the other hand, I'm all for it!

ehird · Post by **ehird** » Sun Mar 18, 2007 9:54 am

There are drivers to make them show as normal drives.

JoeKayzA · Post by **JoeKayzA** » Sun Mar 18, 2007 12:50 pm

For example, Ext2IFS. I use it everyday on my windows machine, for years already, never had problems. You should just use e2fsck from time to time, ext2ifs can get problematic when your fs has slight errors.