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I know, I know, I know. Bear with me.

BTRFS is listed as stable now (wiki page updated Nov of 2015)

https://btrfs.wiki.kernel.org/index.php/Main_Page#Stability_status

The filesystem disk format is no longer unstable, and it's not expected to change unless there are strong reasons to do so. If there is a format change, file systems with a unchanged format will continue to be mountable and usable by newer kernels. The Btrfs code base is under heavy development. Every effort is being made to keep it stable and fast. Due to the fast development speed, the state of development of the filesystem improves noticeably with every new Linux version, so it's recommended to run the most modern kernel possible.

I am working on building a new NAS for my home. I've ruled out ZFS because it just doesn't expand/grow well. My current NAS is mdadm / ext4, no complaints. But, everyone is saying how great btrfs will be "some day". Most of the comments on it are a year old. The Ubuntu wiki on it hasn't been updated since 2013.

I've decided I will try btrfs. I've got decent backup capabilities and I can let this thing run for a few months before making it 'production' to get a good feel.

The first step was upgrading the kernel to one of the latest. This is where I don't understand things very well. I'm running 14.04.3 just because of the LTS. There is no 4.X 'ubuntu kernel' for trusty (14.04.3) yet. I'm assuming the LTS is part of that reason.

I downloaded the 4.3.3 Wily kernel instead. Things seem fine (meaning it rebooted and didn't die).

So, two questions.

  1. Will I regret running the 4.3.3 Wily kernel on a Trusty build?
  2. Would it be better to run btrfs under Ubuntu 15.X?

Any other thoughts/comments are welcome.

Thank you in advance for taking the time to read this.

closed as primarily opinion-based by muru, David Foerster, andrew.46, Luís de Sousa, Pabi Apr 6 '16 at 14:00

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    Hi Chadd, welcome to AskUbuntu! Your question is most useful to other people if you try to keep it 'objective'. The first questions is quite hard to answer because we can't decide for you whether you'll regret it. A better way of asking would be: 'are there any risks involved with running a new kernel on Ubuntu 14.04?'. There's some more information about this here. – Exeleration-G Jan 8 '16 at 9:06
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I think there is no definite answer to your question. Although sometimes there are regressions introduced in Linux Kernel, in general you would always be better off when you run the latest stable kernel you can get. I think this statement is true for every aspect of computing on Linux, btrfs being no exception. But no one will tell you how much exactly it is.

What makes developers flag something as "stable" is not a single event like adding a killer feature, but rather a intuitive/statistical impression of the time trend of the severity and quantity of discovered bugs in the code.

Personally I am using almost exclusively btrfs for 3-5 machines for at least 3 years in various configurations (mixed with layers of lvm, software RAID, bcache and LUKS; I use no btrfs RAID, but I do use snapshots). For last 2 years I found no serious problems with it.

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Will I regret running the 4.3.3 Wily kernel on a Trusty build?

Yes. the idea about LTS Releases is that you are going to use packages only from the release, updates, backports and PPAs for this version. You maybe don't have problems now using the manually kernel from wily, but, if you have some problem or need updates and is related with kernel packages, don't expect any official support from Canonical or the community.

Now, if you are using 14.04 LTS, you can have support extended for kernel packages and xorg via LTS Enablement Stack (https://wiki.ubuntu.com/Kernel/LTSEnablementStack) that gives to you, updates for kernel and xorg from non-LTS version that come later. Now (2016) you can install kernel backported from wily and xenial beta.

Would it be better to run btrfs under Ubuntu 15.X?

No, because non LTS releases only have support for 9 months and if you like to put this in production, you will need to update from 15.04 to 15.10 before use 16.04 LTS now.

Any other thoughts/comments are welcome. 

Today you can try wily (or xenial) kernel from LTS Enablement Stack. But my recommendation is: wait some weeks for release for 16.04 LTS or try 16.04 LTS Beta now. You are going to have better (and stable) support for btrfs with this release and will be supported for 5 years.

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Kernel 4.2 is available for Ubuntu 14.04 and it is default in 14.04.4.

It can be installed by

sudo apt-get install linux-generic-lts-wily

Kernel 4.4 is also available in Ubuntu repositories, but there may be issues with building proprietary kernel modules, like video drivers because of an old version of gcc in trusty.

This should not be an issue for a NAS

Kernel 4.4 can be installed by

sudo apt-get install linux-generic-lts-xenial

And yes I am using btrfs as a filesystem on 14.04 with kernels 4.2 and 4.4

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