A copy-on-write (COW) file system developed by Oracle included in the Linux kernel.

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23
votes
9answers
3k views

How to keep track of changes in /etc/

I would like to keep track of changes in /etc/ Basically I'd like to know if a file was changed, by yum update or by a user and roll it back if I don't like the chage. I thought of using a VCS like ...
16
votes
3answers
2k views

Securely delete files on btrfs filesystem

Sometimes, there's the need to delete a file in a filesystem, and make sure that the file is truly gone. A file that contains sensitive passwords, for example, should be throughly wiped from the disk. ...
15
votes
2answers
4k views

What are the advantages of Btrfs for end users?

Btrfs has begun to gain some momentum in replacing ext4 as the default filesystem of choice for a few distributions such as Fedora Core 16. It is experimentally available in a number of other ...
13
votes
1answer
1k views

How to make a btrfs snapshot writable?

According to the btrfs Readonly snapshots patch it's possible to "set a snapshot readonly/writable on the fly." So I should be able to turn my readonly snapshot (created with btrfs snapshot -r) ...
12
votes
5answers
2k views

Is btrfs stable enough for home usage? [closed]

btrfs has finally found its way into the latest kernels, is it considered stable and safe enough to use in a home backup scenario (as an alternative to zfs) ?
12
votes
4answers
2k views

Why is cp --reflink=auto not the default behaviour?

Why is cp --reflink=auto not the default behaviour? Could it cause any harm to enable it? Is it possible to enable it at compile time, so it is used all across the system, not just in interactive ...
9
votes
4answers
7k views

How to get rid of the “scanning for btrfs file systems” at start-up?

After upgrading from Ubuntu 12.04 to Ubuntu 12.10, I get a message "scanning for btrfs file systems" at starting-up. I don't have any BTRFS filesystem. It delays the booting for about 15 seconds. How ...
9
votes
1answer
364 views

Limit on the number of btrfs snapshots?

I am considering using btrfs on my data drive so that I can use snapper, or something like snapper, to take time based snapshots. I believe this will let me browse old versions of my data. This would ...
9
votes
2answers
4k views

How to create a snapshot in btrfs, and then rollback to it after some work?

What are the commands to use in btrfs in case I want to: create a (read-only) snapshot of a volume; (do some experiments in the volume); and then rollback the volume to the snapshot?
8
votes
2answers
1k views

Arch does not mount btrfs array on boot

As data partition I have a multi-disk btrfs filesystem. My root disk is ext4 Fstab: UUID=290624c6-6b95-41fd-94a1-923ebca64b83 / ext4 rw,relatime,data=ordered 0 1 /dev/sdc ...
8
votes
4answers
8k views

Should a laptop user switch from ext4 to btrfs?

Related to this. I'd like to take advantage of an OS switch to upgrade to BTRFS. BTRFS claims to offer a lot (data-loss resiliency, self-healing if RAID, checksumming of metadata and data, ...
8
votes
4answers
1k views

Why does my desktop lock up when I copy lots of files to a USB drive?

My desktop is usually very responsive, even under heavy load. But when I copy files to a USB drive, it always locks up after some time. By "lock up", I mean: Moving focus from one window to another ...
8
votes
1answer
99 views

Rolling back btrfs subvolume with child subvolumes

Is there a canonical way of rolling back to a subvolume snapshot that has child subvolumes. So for example, this is my btrfs volume layout: ID 257 gen 59802 top level 5 path __active ID 258 gen 59784 ...
8
votes
2answers
1k views

What keeps one side of an rsync so busy?

I've got a Debian machine on my LAN serving as a backup server for the others. It has four HDDs combined into a software RAID 5 md device, on that an LVM, and on that btrfs. Backups are made using ...
6
votes
1answer
1k views

Are there any deduplication scripts that use btrfs CoW as dedup?

Looking for deduplication tools on Linux there are plenty, see e.g. this wiki page. Allmost all scripts do either only detection, printing the duplicate file names or removing duplicate files by ...
6
votes
2answers
522 views

Slow access to btrfs on LVM/

We have this setup on our server: Ubuntu 14.04 (used to be 12.04) 10TB RAID-6 system LVM (one VG, two LV) ext4 partition ( ~2TB) Btrfs partition ( ~8TB) After a reboot last month the system was ...
6
votes
2answers
1k views

How to use btrfs send/receive for transmitting backup snapshots over a slow and unreliable network connection?

I'd like to use btrfs' send/receive feature for transmitting backup snapshots over a rather slow (initial seed of about 50-100GB, upstream bandwith ~1-2MBit/s) and unreliable (daily forced ...
6
votes
1answer
2k views

Move a linux instalation using btrfs on the default subvolume (subvolid=0) to another subvolume

When doing a installation to a root btrfs filesystem, many linux distributions install to the default subvolume. If left unmodified, this layout will force any snapshots or subvolumes to be created ...
6
votes
3answers
2k views

How to create a read-only snapshot in btrfs?

As far as I understand, the snapshots made by btrfs subvolume snapshot are writable by default and are visible at a certain path under the mountpoint of your btrfs volume. How to setup the system so ...
5
votes
1answer
141 views

How do I figure out what's freezing up my machine?

I am running Arch on this machine: 3.40GHz i7 hexacore (4930K) 16GB DDR3 1600MHz RAM 2xSamsung 840 EVO SSDs in Raid0 (using BTRFS raid) When I run VMware on my Arch with a few VMs (2 ...
5
votes
2answers
3k views

How to clone btrfs filesystem into different medium preserving snapshots' sharing data

I have decided to give btrfs raid capabilities a try. I set up a btrfs with sudo mkfs.btrfs -m raid10 -d raid10 /dev/sda9 /dev/sdb9 /dev/sdc9 /dev/sdd9 Now I want to clone my existing btrfs ...
5
votes
3answers
1k views

Why can't a regular user delete a btrfs subvolume

Using a loop-mounted user created btrfs filesystem, with the permissions set correcly, a user is able to freely create btrfs subvolumes: user@machine:~/btrfs/fs/snapshots$ /sbin/btrfs sub create ...
5
votes
1answer
127 views

Why does the mountpoint of my root filesystem change?

When I look at the output of lsblk it will usually show: lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 298.1G 0 disk ├─sda1 8:1 0 1023M 0 part /boot └─sda2 8:2 0 ...
5
votes
2answers
921 views

Modifying a BTRFS filesystem UUID

I've made backups of my BTRFS filesystem using Clonezilla, and have restored one of those backups to a file named 2013-11-29.sda3.img. I need to get some files out of this backup, but there's a ...
5
votes
1answer
916 views

btrfs and the discard mount option on an ssd

I can't seem to find an answer to this so I thought I would ask here: In /etc/fstab and when using the mount command in ext4 you would add the option discard to activate TRIM on an SSD. Similarly ...
5
votes
1answer
283 views

Is there any way in BTRFS to set compression permanently?

I have a USB HDD. I want to mount it with compression enabled. I can do in the fstab of my system or even using udev rules. The problem is that I won't mount my USB HDD on my computer only. Up to ...
5
votes
0answers
369 views

btrfs change after system upgrade broke apt-btrfs-snapshot [closed]

After upgrading (via apt-get dist-upgrade) a Mint 14 Linux box to Mint 15, apt-btrfs-snapshot seems to have stopped working: 18:25:48 [root@galaxy ~]$ apt-btrfs-snapshot list Sorry, your system lacks ...
4
votes
1answer
2k views

Why does btrfs allow to create a raid1 with mismatched drives?

I'm creating a btrfs using sudo mkfs.btrfs -m raid1 -d raid1 <small-disk> <large-disk> or sudo mkfs.btrfs -m raid1 -d raid1 <large-disk> <small-disk> it creates the fs with ...
4
votes
4answers
226 views

BTRFS data integrity (CRC32c) and HDD data integrity (sector ECC)

I'm new to BTRFS and I'm trying to understand why BTRFS use CRC32c while HDD already have sector level data integrity ECC. Is it because BTRFS don't relay on media to have data integrity protection? ...
4
votes
1answer
4k views

When using btrfs, why “Size”, “Used” and “Avail” values from df do not match?

I have a btrfs partition. When I run df -h, it shows: Filesystem Size Used Avail Use% Mounted on /dev/sda2 113G 101G 8.3G 93% /home From Why is that? Is it because reserved space for ...
4
votes
1answer
41 views

How to check (simulate), how much space will be freed after I remove a btrfs subvolume?

The question is not trivial. BTRFS is COW file system and one object stored on hard disk can be referenced by many files. I use BTRFS snapshots as a part of a backup solution on my production ...
4
votes
2answers
867 views

btrfs on openSUSE not releasing disk space

I have an openSUSE 12.1 install on my main desktop running with btrfs filesystem for root (/boot is ext4). I started having issues today with KDE informing me that disk space is almost all gone and ...
4
votes
1answer
221 views

Simulate bitrot/corrupt files (for BTRFS)

Is it possible to intentionally corrupt a file so that BTRFS will report a checksum error? I want to test a script that's supposed to find file names with checksum errors, but I don't have any corrupt ...
4
votes
1answer
1k views

How to delete btrfs subvolumes with <FS_TREE> in their name

I have a bunch of btrfs snapshots like so: 20:17:37 [root@galaxy /]$ btrfs subvolume list -a / |grep apt ID 271 gen 348 top level 5 path <FS_TREE>/@apt-snapshot-2013-04-17_21:44:30 ID 272 gen ...
4
votes
1answer
8k views

How do I fix btrfs? [closed]

I've trawled mailing lists and finally finished up on Ubuntu's btrfs page, and am left feeling that btrfs still does not have a full fixing utility (as indicated on their home page). Even though ...
4
votes
1answer
104 views

ideal btrfs storage scheme to incorporate external USB HDD as backup media

Is there a way to leverage btrfs's advanced features (COW, snapshots, etc.) to continuously backup/mirror my main storage volume to an external USB HDD?
4
votes
1answer
769 views

Understanding btrfs dmesg

Based on the documentation I found at https://btrfs.wiki.kernel.org/index.php/Data_Structures I am strugeling to understand the following dmesg [ 173.946830] device fsid ...
4
votes
0answers
499 views

Compiling and running Snapper for Ubuntu

I am trying to get snapper working in my Mint 14. (The version from launchpad is old and not compatible with Ubuntu 12.10. The OpenSuSe's build project failed to build it, too). So I try my luck with ...
3
votes
2answers
2k views

Is there a way to monitor progress of a btrfs rebalance?

I'm replacing a failed harddrive in a mirrored btrfs. btrfs device delete missing /[mountpoint] is taking very long, so I assume that it's actually rebalancing data across to the replacement drive. ...
3
votes
2answers
263 views

ext4 to btrfs conversion: If I accidentally lose power to the system during the conversion, will I lose the data?

I want to convert the 3TB 80% full ext4 block device into btrfs and I want to estimate the risks involved in the process. If I accidentally lose power to the system during the conversion, will I ...
3
votes
1answer
746 views

Can btrfs handle different RAID levels for different subvolumes?

I'd like to assign different RAID levels to different subvolumes in my btrfs filesystem, eg have a subvolume /home that uses RAID 1 and a subvolume /var that uses RAID 0. Is that at all possible (if ...
3
votes
1answer
199 views

Equivalent of pvmove for BTRFS

Similar to the question I asked a while back. This one's a little easier? I can see there's volume management logic in BTRFS for removing/adding/rebalancing physical drives, but is there a tool to ...
3
votes
1answer
106 views

Mount options for BTRFS on an external USB drive

I've formatted my external HD with BTRFS (aware of the risks). What are options I should use to increase failure tolerance on sudden power loss to the drive?
3
votes
1answer
657 views

Resize a btrfs partition inside a logical LVM volume

Following derobert's trick to resize the underlying filesystem when resizing a LVM volume: lvm> lvextend -r -l +100%FREE /dev/VolGroup00/lvolhome fsck from util-linux 2.25.2 /sbin/fsck.btrfs: ...
3
votes
1answer
330 views

Running du command reports infinity as disk usage

I'm trying to get the total size of what's stored in my home directory. To my surprise, it reports infinity after a few seconds: /home/user $ du -sh . Infinity Huh? I'm pretty sure there are no ...
3
votes
1answer
1k views

Boot partiotionless disk with syslinux

A file system can be configured to span a complete disk, omitting any partition table. Notice intentionally the command to do so does not use /dev/sda1 but the raw, unpartitioned device instead. ...
3
votes
1answer
1k views

How to install Debian Jessie properly onto multiple devices with BTRFS in mode RAID 1?

As a short introduction I'm going to tell you, what kind of setup I have and what I want to achieve. After that I try to explain my problem. Since this is my first question on U&L I have to ...
3
votes
1answer
104 views

Get device with major number 0 (btrfs subvolume)

When I stat a file on a btrfs subvolume I get a major device number of 0. Is there a reliable way to find the mount point of this device, without knowing in advance it is a btrfs subvolume? e.g. I'd ...
3
votes
1answer
373 views

Online remount btrfs of root filesystem with different subvolume (snapshot)

Let's say you have a btrfs root filesystem on an online system. You want to revert the filesystem to an earlier state, of which you have a snapshot: remount /dev/sdaX / -o remount,subvol=snapshots/Y ...
3
votes
0answers
52 views

Running a btrfs RAID 5 array on Arch Linux

For two weeks, I've been trying to run my Raspberry Pi (model B) as root from a btrfs RAID 5 without success. The RAID runs on three 1TB disks /dev/sda, /dev/sdb and /dev/sdc. The three disks were ...