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Btrfs (B-tree FS or Butter FS as in "I Can't Believe This is Butter!" hinting to competition with ZFS) tried to provide Linux an enterprise class file system (the role, for which previously ReiserFS was shooting  before Hans Reiser went to prison for killing his former wife). Like ReiserFS, ZFS and NTFS it is a B-tree based filesystem.

Competition with ZFS was the main driver in development and Btrfs provides  the set of features very similar to ZFS. As of 2012 it is close to production quality and actually was included in SLES 11 SP2 (which was essentially a beta misnamed as a production release ;-). As of Linux 3.2 (released January 4, 2012), Btrfs implements:

  1. Online defragmentation
  2. Online volume growth and shrinking
  3. Online block device addition and removal
  4. Online balancing (movement of objects between block devices to balance load)
  5. RAID0, RAID1, and RAID10
  6. Subvolumes (one or more separately mountable filesystem roots within each physical partition)
  7. Transparent compression (zlib and LZO)
  8. Snapshots (read-only[23] or copy-on-write clones of subvolumes)
  9. File cloning (copy-on-write on individual files, or byte ranges thereof)
  10. Checksums on data and metadata (CRC-32C[24])
  11. In-place conversion (with rollback) from ext3/4 to Btrfs[25]
  12. File system seeding[26] (Btrfs on read-only storage used as a copy-on-write backing for a writeable Btrfs)
  13. Block discard support (reclaims space on some virtualized setups and improves wear leveling on SSDs with TRIM)
  14. Offline filesystem check[27]

Chris Mason, who moved to Oracle from Suse in 2007 started the project the same year . Oracle has released the project under the GPL license. Paradoxically Oracle bought Sun and now owns ZFS so this is kind of internal compertition between two projects. Still Mason and Oracle decided to move on with Btrfs development. Here is a relevant quote from A short history of btrfs [LWN.net]

At the same time that Chris was figuring out the technical design of btrfs, he was also figuring out how to fund the development of btrfs in both the short and the long term. Chris had recently moved from SUSE to a special Linux group at Oracle, one that employs several high-level Linux storage developers, including Martin K. Petersen, Zach Brown, and Jens Axboe. Oracle funds a lot of Linux development, some of it obviously connected to the Oracle database (OCFS2, DIF/DIX), and some of it less so (generic block layer work, syslets). Here's how Chris put it in a recent interview with Amanda McPherson from the Linux Foundation:

Amanda: Why did you start this project? Why is Oracle supporting this project so prominently?

Chris: I started Btrfs soon after joining Oracle. I had a unique opportunity to take a detailed look at the features missing from Linux, and felt that Btrfs was the best way to solve them.

Linux is a very important platform for Oracle. We use it heavily for our internal operations, and it has a broad customer base for us. We want to keep Linux strong as a data center operating system, and innovating in storage is a natural way for Oracle to contribute.

In other words, Oracle likes having Linux as a platform, and is willing to invest development effort in it even if it's not directly related to Oracle database performance. Look at it this way: how many operating systems are written and funded in large part by your competitors? While it is tempting to have an operating system entirely under your control - like Solaris - it also means that you have to pay for most of the development on that platform. In the end, Oracle believes it is in its own interest to use its in-house expertise to help keep Linux strong.

After a few months of hacking and design discussions with Zach Brown and many others, Chris posted btrfs for review. From there on out, you can trace the history of btrfs like any other open source project through the mailing lists and source code history. Btrfs is now in the mainline kernel and developers from Red Hat, SUSE, Intel, IBM, HP, Fujitsu, etc. are all working on it. Btrfs is a true open source project - not just in the license, but also in the community.

Btrfs has a gained a very large following within the Linux community and has whipped up a good deal of buzz. Some of the features of btrfs that have led to this buzz are:

SLES implementation

The SP3 update to SUSE Linux Enterprise 11 (SLES 11) also updates its Btrfs support for handling quotas with sub-volumes and also to provide faster snapshotting, better performance, and other newer Btrfs features. While SUSE has toyed with Btrfs on their enterprise platform, it isn't yet the default SLES file-system.

it is not default filesystem in SLES

It is default filesystem in OpenSuse and sysadmins used to ext2/ext/ext4 might make several mistakes installing it.

First of all btrfs is a merge of filesystem and lofical file manager.

So it does not make sense to subpurtion drive on partitions like /boot, /var, etc like in ext3/ext4. Instread you create single partition mounted as /

 


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[Mar 03, 2015] The SP3 update to SUSE Linux Enterprise 11 (SLES 11) also updates its Btrfs support

handling quotas with sub-volumes improved. It also to provide faster snapshotting, better performance, and other newer Btrfs features. While SUSE has toyed with Btrfs in SLES, it isn't yet the default file-system.

[Nov 27, 2012] Rollback To A Working State With btrfs + apt-btrfs-snapshot On Ubuntu 12.10 by Falko Timme

Nov 26, 2012 | HowtoForge - Linux Howtos and Tutorials

This tutorial explains how you can revert failed apt operations (like apt-get upgrade) and roll back to the previous system state with apt-btrfs-snapshot on an Ubuntu 12.10 system that uses the btrfs file system. apt-btrfs-snapshot creates a snapshot of the system before the apt operation. Being able to easily restore the previous system state after a failed apt operation takes away much of the pain system administrators have to deal with normally and is one of the greatest features of the btrfs file system.

[Sep 07, 2012] Linux Don't Need No Stinkin' ZFS BTRFS Intro & Benchmarks Linux Magazine

Feature
BTRFS
Copy on Write yes
Snapshots yes
Snapshots of snapshots yes
Performance degradation at near 98-100% disk usage Most likely yes
Block level compression Currently a mount option
Disk encryption Planned but not currently in kernel. Encryptfs could be an option
Online resizing yes
Online defragmentation yes
Write checksums yes
Built-in RAID yes (0, 1, 10)
ACL yes
Direct IO Writes yes. Reads No – Planned
Quotas yes

[Mar 16, 2012] SUSE Linux Enterprise Server 11 SP2 review by Koen Vervloesem

Mar 14, 2012 | http://www.linuxuser.co.uk/

Such a big jump in kernel version between service packs is not common for enterprise Linux distributions, which are usually quite conservative. For instance, Red Hat Enterprise Linux 5 is still using kernel version 2.6.18, even for its 8th update (RHEL 5.8), released a week after SLES 11 SP2, and in the same way RHEL 6.2 is still using kernel version 2.6.32. Of course these kernel versions contain a lot of backported features from newer kernel versions, but it's a lot of work to patch these features in and to keep maintaining them.

Instead of backporting and maintaining all those interesting features, SUSE's engineers have decided to use Linux 3.0 for SLES 11 SP2. This wasn't done rashly: they did an extensive code review of Linux 3.0 and verified that the kernel's Application Binary Interface (ABI) is completely compatible with SLE 11′s original 2.6.27 kernel. This guarantees that all software that ran on this kernel can expect exactly the same behaviour from the newer kernel release. So any software that has been certified for SLE 11 is still certified for SLE 11 SP2.

Ext3 is still the distro's default filesystem, but this is the first time Btrfs (which was introduced as a technology preview in SP1) is officially supported. However, SP2 still uses GRUB Legacy which can't boot from Btrfs, so when you choose Btrfs in the installer, SLE uses it as your root file system but creates a /boot partition with an Ext3 filesystem.

SUSE has also integrated the Snapper tool that it introduced in openSUSE 12.1 to manage Btrfs snapshots and rollbacks. The basic idea of Snapper is that it automatically creates a snapshot before and after running YaST or Zypper, compares the two snapshots and therefore provides the means to revert the differences between these two snapshots. You can list all the snapshots, see the differences between snapshots and roll them back using a user-friendly YaST module or with the commandline snapper tool. There's just one caveat: because the boot partition doesn't use Btrfs, you can't roll back kernel updates or changes to the boot configuration.

Thanks to Snapper, you can mess up system configuration changes or package installations or updates without having to restore from an old backup and risking to lose some files. Just revert to the snapshot before your problematic change and you're fine. But Snapper also helps with audits: it's very easy to discover which changes were made by which YaST or Zypper transaction. Snapper also creates cron jobs for periodic snapshots (which is configurable), so you'll be able to undo other manual changes too.

SP2 still offers Xen and KVM for virtualization, but it also introduces support for LXC (Linux containers), which is a form of operating system-level virtualization: when you create LXC containers, they are separate virtual servers, but all running on the same underlying Linux kernel of the host system. This lightweight virtualization method has a negligible overhead, as it's essentially a "chroot on steroids". On SP2, you can use LXC to isolate various system services from each other.


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