Btrfs 0.14, Managing Multiple Devices

Submitted by Jeremy

on April 30, 2008 - 8:36am

"Btrfs v0.14 is now available for download," Chris Mason announced, adding, "please note the disk format has changed, and it is not compatible with older versions of Btrfs." The project has gained a new wiki home page on the kernel.org domain, where it is explained, "Btrfs is a new copy on write filesystem for Linux aimed at implementing advanced features while focusing on fault tolerance, repair and easy administration. Initially developed by Oracle, Btrfs is licensed under the GPL and open for contribution from anyone." Regarding the latest release, Chris explained:

"v0.14 has a few performance fixes and closes some races that could have allowed corrupted metadata in v0.13. The major new feature is the ability to manage multiple devices under a single Btrfs mount. Raid0, raid1 and raid10 are supported. Even for single device filesystems, metadata is now duplicated by default. Checksums are verified after reads finish and duplicate copies are used if the checksums don't match."

Chris offered links to multi-device benchmarks summarizing, "in general these numbers show that Btrfs does a good job at scaling to this storage configuration, and that is it on par with both HW raid and MD." Looking forward, he concluded, "next up on the Btrfs todo list is finishing off the device removal and IO error handling code. After that I'll add more fine grained locking to the btrees."

From: Chris Mason
Subject: Btrfs v0.14 Released
Date: Apr 29, 1:01 pm 2008

Hello everyone,

Btrfs v0.14 is now available for download.  Please note the disk format has 
changed, and it is not compatible with older versions of Btrfs.

For downloads and documention, please see the Btrfs project page:

http://btrfs.wiki.kernel.org

The oss.oracle.com Btrfs project page will soon start redirecting here.

v0.14 has a few performance fixes and closes some races that could have 
allowed corrupted metadata in v0.13.  The major new feature is the ability to 
manage multiple devices under a single Btrfs mount.  Raid0, raid1 and raid10 
are supported.

Even for single device filesystems, metadata is now duplicated by default. 

Checksums are verified after reads finish and duplicate copies are used if the 
checksums don't match.

Multi-device design details can be found here:

http://btrfs.wiki.kernel.org/index.php/Multiple_Device_Support

And sample usage to create and add volumes can be found here:

http://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices

I'm putting up some benchmarks of the new multi-device code as the runs 
finish:

http://btrfs.wiki.kernel.org/index.php/Multi-device_Benchmarks

Next up on the Btrfs todo list is finishing off the device removal and IO 
error handling code.  After that I'll add more fine grained locking to the 
btrees.

Thanks to everyone who has helped contribute to and test this release.

-chris
--

Link

andy

April 30, 2008 - 8:36pm

The "multi-device benchmarks" link needs to be corrected.

Update: Looks like it's fixed now. The magical reload button did it. ;^)

Update #2: Nope, it's right on the viewing page but wrong on the kerneltrap.org front page.

GPL

ig (not verified)

April 30, 2008 - 9:30pm

This is great stuff. And it probably would never have come into existence if Sun wasn't so stupid about licensing ZFS. They deliberately avoided GPLing ZFS specifically to keep it off of Linux. And now the open source community, led by Oracle, is doing a better and more open filesystem.

Let this be a lesson to Sun and everyone else: license your technology on favorable terms, or you will be sidelined.

and what would Sun gain by releasing ZFS under GPL?

Tomasz Chmielewski (not verified)

May 1, 2008 - 1:03am

I don't want to start any flame - but what would Sun gain by releasing ZFS under GPL?

Even more users flowing from its Solaris system to Linux - I wouldn't call it a gain.

If OpenSolaris were GPLv2,

Anonymous (not verified)

May 1, 2008 - 2:56am

If OpenSolaris were GPLv2, they could port linux drivers quickly. Then they had a chance to make distributions as usable as Ubuntu or Fedora. I'm sure many users would also flow from Linux to Solaris. Both Linux and Solaris would win.

"Porting linux drivers

Anonymous (not verified)

May 1, 2008 - 10:36pm

"Porting linux drivers quickly" is such a red herring in the OpenSolaris/GPL debate. The two OSes are sufficiently different in their respective DDIs that one would probably save time by writing the thing from scratch.

Also, one could also say that it's the Linux kernel's license that prevents it from accepting non-GPL code. Not everything in the world has to be GPL, you know. Linux people are the first to trumpet about choice and freedom except when it comes to this subject. Then the tone changes and there can be only one (license).

"Also, one could also say

Anonymous (not verified)

May 3, 2008 - 12:35pm

"Also, one could also say that it's the Linux kernel's license that prevents it from accepting non-GPL code"
Non-GPL _compatible_ code, thankyouverymuch.

GPLing ZFS keeps it off the {Free|Net|Open}BSD

Matthias G. (not verified)

May 2, 2008 - 1:57am

This is the typical viewpoint of GPL people.

If Sun would license ZFS only under GPL, then all the BSD variants could not include ZFS. In the moment there is a kernel implementation for FreeBSD. For NetBSD this is already started.

Because of this, I would blame the GPL licence for being to restrict for including other code. I would not blame the CDDL license or BSD license for this shortage. They allow the usage of the code mixed together with other licenses in contrast to the GPL.

(Yes, I also use certain software, which is licensed under the GPL...)