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

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26
votes
9answers
4k 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 ...
21
votes
1answer
4k 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) ...
20
votes
3answers
6k 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 ...
19
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. ...
16
votes
4answers
3k 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 ...
13
votes
1answer
1k 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 ...
13
votes
4answers
11k 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 ...
12
votes
5answers
3k 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
2answers
7k 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?
10
votes
3answers
2k 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 ...
10
votes
1answer
141 views

How to duplicate a file without copying its data with btrfs?

I have no experience with btrfs, but it's advertised to be able to de-duplicate files. In my application, I'd need to duplicate whole directory trees. From what I learned, btrfs only de-duplicates ...
10
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 ...
9
votes
4answers
10k 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, ...
9
votes
1answer
3k 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 ...
9
votes
1answer
158 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 ...
9
votes
2answers
2k 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 ...
8
votes
1answer
2k 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 ...
8
votes
2answers
3k 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
2answers
3k 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 ...
7
votes
1answer
829 views

Why does “cp -R --reflink=always” perform a standard copy on a btrfs filesystem?

Btrfs support Copy-On-Write. I tried to use that feature to clone a directory: cp -R --reflink=always foo_directory foo_directory.mirror I expected the command to finish almost instantly (like a ...
7
votes
3answers
2k 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 hitch....
6
votes
2answers
2k 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
4answers
677 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? ...
6
votes
1answer
6k 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 ...
6
votes
3answers
3k 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 ...
6
votes
1answer
912 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 ...
6
votes
1answer
64 views

Make tar (or other) archive, with data block-aligned like in original files for better block-level deduplication?

How can one generate a tar file, so the contents of tarred files are block-aligned like in the original files, so one could benefit from block-level deduplication ( http://unix.stackexchange.com/a/...
6
votes
1answer
887 views

Is btrfs suitable as backup filesystem?

Right now I have a pretty traditional backup filesystem structure on top of ext4. Every time a backup is made, a new folder backup-DATE is created to which files are rsync'ed (with hardlinks made ...
6
votes
1answer
4k views

Clear unused space with zeros (btrfs)

How to clear unused space with zeros ? (I am asking for tool for btrfs filesystem) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like ...
6
votes
0answers
136 views

How to delete a directory with multiple btrfs subvolumes?

My root file system is on a btrfs partition. My /chroot directory has a number of btrfs subvolumes in it which prevent me from deleting it with rm -rf /chroot. In an attempt to delete all the ...
6
votes
2answers
175 views

How do I layer compression on top of encryption on top of BtrFS, per-file?

BtrFS should support this really, but it doesn't. So ECryptFS looks like it will fill the gap. The only thing is, how would I layer compression on top of this? Reasons for compression on top of ...
5
votes
3answers
5k 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. ...
5
votes
3answers
6k 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
1answer
973 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
1answer
4k 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: ...
5
votes
1answer
1k views

How to replace a device in BTRFS RAID-1 filesystem?

I have a BTRFS RAID-1 filesystem with 2 legs. One disk needs to be replaced because of re-occuring read errors. Thus, the plan is: add a 3rd leg -> result should be: 3 way mirror remove the faulty ...
5
votes
1answer
4k views

btrfs ERROR: error during balancing - No space left on device

My Kubuntu 12.04 system ran out of space on on the root partition and will not boot. The command df -h shows a lot of space available (with only 37% used): /dev/sda2 45G 17G 29G 37% ...
5
votes
2answers
4k 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 ...
5
votes
1answer
2k views

Abysmal general dm-crypt (LUKS) write performance

I am investigating a problem where encrypting a block device imposes a huge performance penalty when writing to it. Hours of Internet reading and experiments did not provide me with a proper ...
5
votes
2answers
1k 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 ...
5
votes
1answer
140 views

How do I 'upgrade' existing BTRFs to be fully redundant

How would I convert an existing BTRFs pool, within Debian Jessie (4.2 Kernel) that I created with... sudo mkfs.btrfs /dev/sdb /dev/sdc /dev/sdd ...into being fully redundant, or as redundant as it ...
5
votes
1answer
1k 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 ...
5
votes
1answer
250 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
1k 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
0answers
613 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
3k 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
2answers
5k views

Clear all Snapper snapshots

OpenSUSE (among other distributions) uses snapper to take snapshots of btrfs partitions. Some people think the default snapshot intervals take up too much space too quickly, but whether or not you ...
4
votes
2answers
159 views

btrfs filesystem end offset (image size)

I have a btrfs filesystem of about 7G in a 10G image file img.btrfs (I shrank it using btrfs fi resize -3G /mnt). How can I find the total size (end byte offset) of the filesystem, so that I can ...
4
votes
2answers
120 views

How to find out if a file on btrfs is copy-on-write?

I know that cp has a --reflink option to control full copies vs. copy-on-write "copies". On btrfs, can I use ls (or some other command) to find out whether a file shares (in a copy-on-write senses) ...
4
votes
1answer
82 views

What is the proper way to unlock a root filesystem spanning two LUKS devices by only entering the password once, using systemd?

I have been having a lot of issues getting an encrypted multi-disk root filesystem to boot up reliably under systemd on Debian Jessie while only having to enter the password once. Previously I've ...