Disk partitioning and formatting?

[mr_raider]

I tried BTRFS in a VM and noticed that if I create a single / partition, Ubuntu creates entries fro @ and @home in fstab. I assume these are sub volumes? for / and /home?

What is the advantage of this setup?

[oshunluvr]

Yes, they are subvolumes. The advantages to btrfs are numerous and discussed here in many posts. Specifically to this case: the primary advantage is all free space on a file system is available to all subvolumes on that filesystem. So if you have 200GB free space - both your installed OS and your /home can use that free space as needed, while still segregating your home from your root install.

[mr_raider]

Yes, they are subvolumes. The advantages to btrfs are numerous and discussed here in many posts. Specifically to this case: the primary advantage is all free space on a file system is available to all subvolumes on that filesystem. So if you have 200GB free space - both your installed OS and your /home can use that free space as needed, while still segregating your home from your root install.

The main advantage for separate home and root is that I can wipe just the root partition in case of a re-install and keep the home partition. How do you do that with sub volumes?

[oshunluvr]

The main advantage for separate home and root is that I can wipe just the root partition in case of a re-install and keep the home partition. How do you do that with sub volumes?

Couldn't be simpler:

btrfs subvolume delete @/

No formatting or partitioning required.
Or; what if you want to re-install but not wipe your old install right away? Just rename the old subvolume and re-install.
Want to make a total backup of your home? Simply copy the subvolume.
Want to preserve your install at it's current state before installing a new program? Take a snapshot

btrfs subvolume snapshot @/ @/snapshot1

Running low on hard drive space? Add in a second drive or another partition without reformatting or even logging off!

btrfs device add /dev/sdb /mnt/sda

One thing I do is after install, I rename both the / and /home subvolumes to unique names (editing the associated fstab and grub files too of course). Than I can install a new version along side the old any time I want. I current have these subvolumes on a 2 drive SSD btrfs RAID:

@Kubuntu_12_04
@Kubuntu_13_10
@Kubuntu_13_10_140315
@Kubuntu_13_10_home
@Kubuntu_14_04
@Kubuntu_14_04_home
@Neptune3_1
@Neptune3_1_home

Each of these installs are bootable, including @Kubuntu_13_10_140315, which is a snapshot I took on March 15,2014 of my 13.10 install.

As you can see the benefits of btrfs are numerous.

[mr_raider]

Any quality write up with btrfs and SSDs?

Sent from my Nexus 5 using Tapatalk

[oshunluvr]

Any quality write up with btrfs and SSDs?

I and at least one other forum member here have been using btrfs as our primary filesystem for more than 3 years now and both of us on SSDs. In 3 years, I have had one reported error that cropped up that did not cause any loss in data and was easily fixed with a simple command. It was due to the type of filesystem compression I was using at the time and I was able to correct it on-the-fly (without unmounting or rebooting). The other user has had similar success.

I use btrfs on my server with 4 large hard drives, my desktop with 2 SSDs and 3 HDDs, and my netbook with a very small SSD. All of these systems benefit from different aspects of btrfs.

I wouldn't hesitate to recommend using it, with a couple of exceptions: btrfs does not yet handle swap files via loop mounting (systemd does so you could still do that if desired) and does not handle virtual drives (like VMWare or VirtualBox). My solution to these small limitations is to use a HDD to hold my virtual drive and use a swap partition.

From a pure performance perspective; a full-blown 4-drive RAID0 array is faster and has more available space using properly tuned ext4 than a 4-drive btrfs array using RAID0 for data and RAID1 for metadata, but it's a small difference in speed and file space and not noticeable in real world use. Besides, the work load to create and maintain the RAID array far exceeds the slight benefit IMO.

[GreyGeek]

I second what Oshunluver says, with one addition: btrfs does not work will with dynamic virtual hds on VirtualBox, but it does work with fixed size virtual drives. I've been using btrfs on Trusty since I installed Trusty when it went Alpha, in January. Zero problems. I experimented a lot with the various btrfs capabilities and add-on tools. The only one I would NOT recommend is apt-btrfs-snapshot, because it creates so many subvolumes, automatically, that allowed to go unfettered it was eating my 360GB HD partition like it was candy. Even restricted to the minimum number of subvolumes (5), it continued to eat up space. The concept that app is based around is nice, but it turns out it is just as easy to do what it does manually, and you have complete control, like recovering from a bad update. There was a large thread created, which Oshunluver started and I added my experiences to, that has lots of info and links.

https://www.kubuntuforums.net/showth...btrfs-snapshot

https://www.kubuntuforums.net/showth...d-a-new-drive!

https://www.kubuntuforums.net/showth...Let-s-upgrade!

[Teunis]

I am very tempted to go btrfs but am held back because there is no (working) Windows driver.
Last time I dabbled with btrfs I found out the Hard Way that in a mixed ext4 / btrfs system it wasn't supported/recognised by Grub-update, I assume that's no longer a problem.

[oshunluvr]

Last time I dabbled with btrfs I found out the Hard Way that in a mixed ext4 / btrfs system it wasn't supported/recognised by Grub-update, I assume that's no longer a problem.

That has been fixed.