Between ext3, ext4, reiserfs and others, Ubuntu has no shortage of file systems to choose from when installing a new system. And those options are set to become yet more numerous in Ubuntu 10.10, which will introduce support for btrfs. Wondering what this new file system is all about and why it might matter to you? Read on for an introduction.
Introduced last year, btrfs is a new file system intended to address the shortcomings in ext4, which is currently the default choice for Ubuntu and most other Linux distributions. While ext4 is pretty robust and efficient, it lacks some advanced features, such as support for snapshots and advanced scalability, that are particularly important in the enterprise environment.
As ext4 developer Ted Ts’o has stated, the file system that currently predominates in modern Linux distributions was never intended to be a longterm solution. It was created only as a temporary means of addressing the problems with its predecessor, ext3, until something like btrfs could be brought to maturity.
The ultimate aspiration of the developers behind btrfs is to bring the power of Sun’s venerable ZFS file system to Linux. btrfs still has a ways to go before all the features of the latter are implemented, but even as it exists in Ubuntu 10.10, btrfs offers a number of improvements over ext4 and its other competitors.
btrfs in Maverick
btrfs is not yet stable, but it’s close enough for Ubuntu 10.10 to support its use for root file systems. If you’ve tested the alpha builds of Maverick, you may have noticed btrfs listed as a file system choice in the Ubuntu installer. The last I checked, the option didn’t actually work under the live CD, but it does from the alternate CD.
In addition to creating new systems from scratch on a btrfs partition, existing ext4 file systems can be converted to btrfs easily and safely using the btrfs-convert tool. The one catch is that /boot can’t be on btrfs, so it would have to be moved to a separate partition if it’s not already.
Another of the cool features in btrfs is support for snapshots using btrfsctl, which make it possible to save the state of a live system instantaneously and revert to it at any later point. This is certainly a useful tool on servers, where incremental backups are crucial, but it is applicable on the desktop as well: Fedora already has a system that uses btrfs snapshots to allow users to test new software packages and easily roll back to a stable system in case something goes wrong. This is a fantastic idea, and I’d love to see Ubuntu implement it as well.
On the performance front, Phonorix did some benchmarking last February in which btrfs came out behind ext3 and ext4 in most tests. Those comparisons are already outdated, however, and we can expect btrfs’s benchmarks to improve as development continues.
Stability
As far as production goes, btrfs is not yet an appropriate choice; as its documentation makes explicitly clear, it is “not suitable for any uses other than benchmarking and review.” So while the Ubuntu installer might provide btrfs as an option, I wouldn’t go putting it on the root partition of any production system until it has matured a little more.
All the same, the new file system promises a number of significant advances on both Ubuntu desktops and servers. In my experiments with it, it’s also worked pretty well, and I’m excited to explore the new possibilities it offers to Ubuntu users as it continues to develop.
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I used btrfs with maverick and it was pretty slow, boot times ranged from 30 secs to about a minute at times, never came close to the ext4 boot times.
Id advise people to stick to ext4
How would the snapshot features of btrfs compare to Microsoft Windows Volume Shadow Copy?
zfs venerable? don’t think so! zfs is currently the best file system out there with features that others don’t even dream about. the most advanced file system is not venerable!
From the user perspective, I just can’t understand ZFS isn’t the filesystem of choice in the first place. It’s technically completely feasible and working, it’s open source, but just because the *license* is incompatible with the Linux kernel, it’s being ignored.
Now (again from the user perspective) how f***ed up is that?
@poutsoklis
What you say makes no sense. You say ZFS is the best, but then you say it isn’t venerable. Maybe you don’t know what venerable means. Venerable means “accorded a great deal of respect”.
[...] Ubuntu 10.10’s New File System: btrfs, A Closer Look Between ext3, ext4, reiserfs and others, Ubuntu has no shortage of file systems to choose from when installing a new system. And those options are set to become yet more numerous in Ubuntu 10.10, which will introduce support for btrfs. Wondering what this new file system is all about and why it might matter to you? Read on for an introduction. [...]
I hope a Windows driver will be available. It would be great to make this my default fs on my external hard drives and still be able to access it from Windows. I HATE having to use NTFS on my external hard drives.
I have tested btrfs since shortly after it was added to the kernel. It works and works well. The biggest issue I have with it is that there is no effective fsck. This is being worked on. Once it has a working fsck I’ll be a lot closer to starting to use it as my primary fs.
I’ve been using btrfs on Fedora for almost a year now. Initially just for my /home partition, but more recently I switched my root partition over to it too after ext4 ate some of my data. I know it’s still “experimental” so I won’t cry if it nukes my system and sets my cat on fire, I have all my important data backed up anyway. it’s been rock solid so far and in my experiences every bit as snappy as ext3/4 (your mileage may vary). I do miss not having a proper fsck at the moment, but on the positive side I love the transparent compression that not only makes data take up less space but also speeds up the system in some instances (though it slows it down in other instances).
Oh, awesome, Linux now has new name ‘Ubuntu’.
Plz elaborate on the link between Ubuntu and Linux kernel development. It seems a bit far fetched. Even the canonical management/engineers seem desinterested with Linux development.
[...] Between ext3, ext4, reiserfs and others, Ubuntu has no shortage of file systems to choose from when installing a new system. And those options are set to become yet more numerous in Ubuntu 10.10, which will introduce support for btrfs. Wondering what this new file system is all about and why it might matter to you? Read more here [...]
@AnonyMou.se, Ubuntu is a version of Gnu/Linux, not just Linux (the Kernel). Yes, Ubuntu Gnu/Linux is a great distribution and if it can make Gnu/Linux more popular, more Power to it, I say. Also, @ iGadget, the licensing of ZFS is up to the people who make it, not us users! If they don’t want to “free” it up, they won’t be as popular as other filesystems. They probably want to milk their Sun “purchase” for everything that it’s worth. Happy travels.
A ways?
A (singular) ways (plural)
This bit of American vernacular (“hick talk” as they say) has no place her. Please show some respect for your readers.
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nip: you’re right that Canonical contributes little to kernel development and didn’t develop btrfs. But Ubuntu uses btrfs so we thought it appropriate to cover here. As for the question of whether or not Canonical is a leech, I think that’s already been fleshed out ad nauseam over the last couple weeks in the wake of DeKoenigsberg’s angry blog post (and subsequent apology), so I won’t revisit it here.
Pj: thanks for the grammatical point–I confess that I don’t always respect the AP Stylebook. On the other hand, you’ll see that I always wrote “Web site” even before “website” was deemed acceptable, so perhaps that makes my recent colloquialism somewhat forgivable.
Well, I have used Ubuntu Maverick Alpha 3 with the btr file system, and it works great. It offers a great deal of speed improvement from ext4, which is a help sense I run Ubuntu from a flash drive since my HD was damaged. Now, a timed bootup of the system is exactly 23 seconds. On my SSD I received in place of the HD, its about 5 seconds; fast enough it wouldn’t even need the boot screen, cause it feels like I get passed the BIOS and I’m already at the login.
I tried btrfs for about a year now and the last months it really matured with the 2.6.35 kernel. My biggest concern is the lack of a real fsck but thats being worked on right now.
There is a project Next3 which has added snapshots to ext3 and is being worked on being converted to using the EXT4 format. I wonder how long this conversion would take and how attractive btrfs looks after the conversion is completed. Btrfs has more features than snapshots. I think this would be another stopgap measure.
There is a project to get zfs working on Linux.
http://zfsonlinux.org/