Ext3cow Versioning File System Released For 2.6

Zachary Peterson writes "Ext3cow, an open-source versioning file system based on ext3, has been released for the 2.6 Linux kernel. Ext3cow allows users to view their file system as it appeared at any point in time through a natural, time-shifting interface. This is can be very useful for revision control, intrusion detection, preventing data loss, and meeting the requirements of data retention legislation. See the link for kernel patches and details."

True undelete

[ex-geek]

Undelete, not half-assed, desktop based trash can implementations, is something I've always been missing on Linux. And yes, I generally know what I'm doing, but i'm also human and do make mistakes.

Re:Can No One Else INNOVATE?

[heffrey]

What evidence do you have that this is reverse engineering?

Or do you mean that they are re-implementing Time Machine?

Re:Excellent work but...

[ajs318]

The Linux kernel will never, ever have a stable ABI. Compatibility across versions is guaranteed only at the Source Code level, not the binary level. This is 100% intentional, and the only people it really hurts are those who would deny us access to the Source Code. And they deserve it.

Re:Can No One Else INNOVATE?

[beezly]

Go away MacTroll...

Veritas VxFS has had this for years. Snapshotting has been implemented in the Linux LVM layer for ages. This is just another way to do it.

I don't know anything about the technical implementation of Vista Shadow Copies or Apple's Time Machine, but if it's anything like ZFS [wikipedia.org] then I'll be impressed. I believe there are rumours about the next release of OS X using ZFS (which was developed by Sun), but I'll believe it when I see it.

Re:Excellent work but...

[Anonymous Coward]

How about us who don't want to recompile everything whenever a new kernel release comes out? It is a freaking pain in the butt.

Re:Excellent work but...

[oliverthered]

Your wrong, it also hurts those people who write drivers that aren't accepted into the kernel. And it also hurts end users or haven't you noticed the lack of Linux drivers for a lot of hardware.

Re:Excellent work but...

[Toffins]

Compatibility across versions is guaranteed only at the Source Code level

(Disclaimer: Linux is excellent) But is compatibility even guaranteed at source code level?
Here are some specific examples where source level API changes have occurred:

1. Consider that up to linux-2.6.6 all SATA disks were treated as IDE PATA disks accessible via /dev/hd*, but in linux-2.6.7 they started to be treated as SATA disks only accessible via /dev/sd*. This changeover caused existing SATA disk systems to become unbootable after upgrading to linux-2.6.7 because the boot device at /dev/hd* was no longer accessible. Never documented in kernel/Documentation/*

2. And between linux-2.6.15 and linux-2.6.20 the way the usb subsystem handled usb devices was changed so that usermode usb drivers like the usermode speedtouch driver was broken due to kernel returning EINVAL from each USBDEVFS_SUBMITURB command which is required after a USBDEVFS_CONTROL command issued by the modem_run ADSL line monitoring process. This generates thousands of error messages per second via syslogd. No news of this particular aspect of the usb changes was ever documented in kernel/Documentation/*.

Re:Excellent work but...

[ajs318]

How about us who don't want to recompile everything whenever a new kernel release comes out? It is a freaking pain in the butt.

No it isn't. That's a filthy lie made up by people who want to sell you pre-compiled binaries and stop you mucking about with the Source Code, and nobody who can spell 'make clean && make install' believes it. (Or you could use Gentoo, which automates the recompilation; or a distribution using pre-compiled .rpm or .deb binary packages, which will have been recompiled for you by the distro's own team.)

Anyway, not everything will change at one time. You only need to recompile such applications and libraries as actually break.

Re:Excellent work but...

[Doug Neal]

A huge number of problems in Windows can be attributed to its lack of package management. Every installer is pretty much allowed to do whatever it wants, put files where it wants, change registry keys, whatever.. and when was the last time you saw a Windows program with an uninstaller that worked? I mean really worked? They all leave crap lying around afterwards that they "couldn't" remove for some vague/unspecified reason. Sometimes you don't even get an uninstaller at all. There's no version tracking, and no management of dependencies. Everything just has to ship with all the libraries it needs and hope it doesn't break anything else, which it doesn't always manage. You end up with a total mess, even if you're careful. Your average Windows PC needs reinstalling once a year at least to stay usable, on almost all of the occasions that someone's asked me to check out a few problems on their computer, I've ended up reinstalling just because it would be quicker than to clear up the mess.

The "dependency hell" that you speak of has been a non-issue for years, even Red Hat makes a passable stab at it these days.. there's plenty of issues stopping Linux becoming a mainstream desktop OS but package management isn't one of them. Users don't want to have to run installers from CDs or whatever as you described, it's just what they're used to doing at the moment. If you showed a complete computer novice Synaptic or Click N Run, and then showed them the equivalent in Windows, which do you think they'd prefer?