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

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List reflink filenames to a file on btrfs

Given a path/filename on a btrfs filesystem, how can you see the other reflinked path/filenames to the same file?
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0answers
12 views

Modifying a file “pointed” to by a lot of snapshots

I'm using btrfs and snapper. So, I have many periodic btrfs snapshots, which are marked read-only (can of course be changed by btrfs to r/w and changed back.) Let's say during my initial install I ...
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35 views

BTRFS RAID6 array is broken, how do I fix it?

I have a server running a btrfs raid 6 array which seems to have broken. When try to mount it I get the following error message. I don't know how or why it broke maybe a power outage or something (it ...
3
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1answer
3k 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 ...
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0answers
28 views

Does this bug indicate an error in my btrfs filesystem of simply a bug in the 4.2.0-RC5 kernel?

I'm not sure this is the right place to ask this... I have been running a pre-release kernel (4.2.0-rc5) and yesterday had a possible disk error on my 6-disk raid-1 btrfs filesysystem. While trying ...
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0answers
14 views

Will btrfs snapshots ever share page cache?

It's common to run multiple container images based on the same parent. In theory you should be able to share page cache between these containers automatically. E.g. some of the code in shared ...
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0answers
13 views

How to know perfect filesystem parameters for flash drive format

I have a flash drive and using btrfs on it with default parameters. And now I'm going to slightly improve read/write speed. I see that "play the game" with page and sector size can helps me. But ...
0
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0answers
17 views

How to throttle system resources during transfer from btrfs on file image on cifs mount?

I have a btrfs on a sparse file image (4TB) on a cifs mount of a remote NAS (Synology DS214) with zlib compression enabled. Transferring file from and onto the btrfs causes freezes of Linux (where it ...
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3answers
3k 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. ...
2
votes
1answer
44 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 ...
2
votes
1answer
33 views

Mounting a btrfs image file

I am trying to perform a recovery operation on a btrfs image file that I have extracted using # dd if=/dev/sda1 of=/mnt/sda1.img The file seems to be properly extracted: $ file sda1.img sda1.img: ...
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vote
1answer
34 views

Booting off raid'ed > 2GB drives, btrfs, handling bios boot partition [duplicate]

Setting up an array of (3) 5GB drives using btrfs. It will soon grow to (6) 5GB drives. Starting with raid 1, will rebalance once all the drives are installed to either raid5, 6, or 10. I will be ...
0
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0answers
34 views

where to compress=lzo, btrfs with virtual disk images, with their vm's internally using btrfs

I've been using compress=lzo on my btrfs volumes, because I read this fast compression method actually increases drive performance. (Haven't tested myself.) I'm starting to use ...
0
votes
1answer
43 views

btrfs on LVM on LUKS - one LUKS container performs WAY better than the other

I have 2 LUKS containers, one with default OpenSUSE installer settings, another one with -h sha512 -s 512 -i 5000 and detached header. On top of each of them there is LVM - one with only 1 OS volume ...
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0answers
17 views

btrfs scrub history disappeared

I had some corruption on a multi-disk RAID1 scrub setup and was running the command: watch -n10 -d ;btrfs file usage -T -g /mnt/b;echo;btrfs scrub status -d /mnt/b' After the scrub finished, I ...
1
vote
1answer
25 views

udisksctl mount a different subvolume of an already mounted btrfs partition

I have a btrfs partition with several subvolumes, one of which is /. I have another subvolume with some other stuff that I also want to mount, but trying to mount it with udisksctl: udisksctl mount ...
1
vote
1answer
33 views

Btrfs distribute files equally across multiple devices

I have a btrfs volume across two devices that has metadata RAID1 and data RAID0. In the event one drive would fail, practically all files above the 64KB default stripe size would be corrupted. As this ...
3
votes
1answer
87 views

How to get error detection and correction on a single hard drive on linux (with btrfs or other methods)

One of the cool things about btrfs on linux is that it can correct bit rot if it has redundant data because of its per-block checksumming. I can get redundant data by setting up a raid1 with two ...
0
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1answer
27 views

Btrfs RAID1 mismatched sized drives full

I have a 500 GB HDD and a 300 GB HDD. I have formatted them as btrfs raid1 between. The total size is 800 GB. If I copy 50 GB onto the filesystem, it causes 100 GB to be used. If I copy 300 GB onto ...
1
vote
1answer
56 views

Using Btrfs to eliminate corrupted archives

I am trying to get my personal filesystem in order I want to tar everything and get it organized into proper directories I have many HDDs and a few SSDs I want to use Btrfs with it's checksum and ...
2
votes
1answer
83 views

Is there a simple way to move btrfs subvolumes to a different btrfs filesystem?

I have two separate btrfs filesystems which I would like to consolidate. The subvolume structure looks like this: / filesystemA |- subvolume1 |- subvolume2 |- ... |- subvolumeN / filesystemB |- ...
0
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1answer
28 views

btrfs how to move submolume to another disk

I've got 4 drives in my server: sd{a,b,c,d}. All of them are in a raid1 system. 2 of those drives, sd{b,c} are completely empty. RAID1 will only make one copy of a file on a different drive. So it ...
1
vote
1answer
34 views

Snapper to only take snapshots if something has changed, or at a lower cadence

I'm using snapper for automatic timeline snapshots of my filesystem. The issue I have is that it continues to take hourly snapshots even when nothing on the filesystem has changed, which causes the ...
6
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1answer
395 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 ...
1
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1answer
48 views

btrfs - missing space, what is taking it up?

I have a Netgear NAS device which uses btrfs filesystem. du reports all the files on md device taking up 1.37 TB. btrfs fi df says, that it's taking up 1.53 TB. I cannot figure out where does 0.16 ...
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0answers
38 views

How should I approach designing my btrfs pool/s? [closed]

I am vaguely familiar with a few COW/modern filesystem concepts, and am nowhere near an expert or even beyond neophyte status when it comes to btrfs. I've just installed Rockstor on a machine I intend ...
2
votes
1answer
44 views

Copy BTRFS partition to external harddisk BTRFS partition including snapshots

I have a question about backuping BTRFS partitions. Assume I have a BTRFS partition on /dev/sda1 and an external harddrive with BTRFS on /dev/sdb1. I already found out I can make an initial backup ...
0
votes
2answers
225 views

Btrfs subvolume questions

Just a few questions about Btrfs: Do I have to mount a Btrfs filesystem before creating subvolumes on it? Can I easily convert an existing directory into a subvolume? (i.e. if I want to make "/home" ...
2
votes
1answer
233 views

Understanding btrfs disc usage for single data volume

On my 256 GB disc: # btrfs fi show /dev/sdd3 Total devices 1 FS bytes used 143.43GiB devid 1 size 234.22GiB used 234.22GiB path /dev/sdd3 Btrfs v3.12 I don't understand the discrepancy between ...
3
votes
3answers
2k views

How to remove an empty directory (btrfs filesystem)?

I'm using the experimental btrfs filesystem. My directory looks like this: ls -la empytfolder total 4 drwxr-xr-x 1 root root 0 19. Mär 14:00 . drwxr-xr-x 1 root root 298 19. Mär 13:59 .. I ...
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0answers
27 views

Display btrfs subvolume tree

Is there a way to make a btrfs subvolume tree like what is shown below? (Only subvolumes - no regular directories or files.) # tree /mnt/1 /mnt/1 ├── a ├── snapshot │ ├── a │ └── subv └── subv ...
9
votes
2answers
5k 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?
4
votes
2answers
61 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 ...
5
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 ...
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0answers
25 views

btrfs device add: different mount options than for seed?

I have a btrfs seed device, created with mixed data+metadata (mkfs.btrfs --mixed), and also --metadata single. This device is read-only. When doing btrfs add device /dev/sdc1 /mnt, is it possible to ...
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0answers
115 views

ssd caching in loop device on btrfs

I have an ssd and 2TB hard disk. The ssd is used for the root filesystem which uses only around 20G of the 120G available. Is there a way to use an image/loop on the root filesystem (btrfs) as a cache ...
3
votes
1answer
26 views

Using btrfs to sandbox programs

First, for this post, I'm using the term sandbox to really mean separation of filesystem changes only. Neither of these methods would: isolate processes in the sandbox from interacting with other ...
2
votes
2answers
40 views

Conceptualizing btrfs - understanding snapshots, and space used

Just starting to learn about btrfs and considering switching. My current thought of btrfs is that operates pretty much like git, with everything tracked, and a commit happening every 30 seconds after ...
1
vote
1answer
118 views

How do you mount a specific btrfs subvolume?

Suppose I start with a non-btrfs system and then add a secondary drive that I format as btrfs. How would I mount /var/log on a subvolume of the new drive instead of on the original drive? Is this even ...
2
votes
1answer
93 views

Is BTRFS saying that my HDD is dead?

I noticed that my HP N54L was laboring and discovered that dmesg was reporting this: [ 81.945530] btrfs read error corrected: ino 1 off 16685977600 (dev /dev/sdb sector 2636776) [ 82.010023] ...
3
votes
1answer
57 views

Are tars deduplicatable at the block level?

Quite simply, when a tar file is made on disk, would the extents be deduplicatable with extents inside and/or outside of the tar? I am asking in the theoretical sense, so if the extents of data are ...
12
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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 ...
2
votes
1answer
87 views

Is `--reflink=auto` safe to set as default for cp?

I am currently a user of BTRFS and would like to take advantage of the CoW such that when files are copied on the same btrfs filesystem, they are automatically deduplicated by reusing the existing ...
2
votes
1answer
51 views

Show mounted btrfs subvolumes?

Is there a command to show which btrfs subvolumes are mounted on each mountpoint? Alternatively, is there somewhere (e.g. in the /proc or /sys trees) where the information can be read? The output ...
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0answers
37 views

btrfs - snapshot of a parent subvolume excludes child subvolumes?

Let's say I want to exclude ever-changing logfiles from backups. Parent subvolume / Child subvolume /log I snapshot /. Looking at the snapshot, /.snapshots/today/log will be empty, correct? This is ...
0
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0answers
34 views

Whats the right way of Data/Subvolume structure/hierarchy management using btrfs

My intention is to switch my filesystem from ext4 to btrfs. Currently I have 2 space disks with 4 TB each. I allready set them up in raid1 (using mkfs.btrfs -d raid1 /dev/sdx /dev/sdy) Then there ...
0
votes
1answer
121 views

How to mount btrfs partition?

I've installed xbian distro on RPi. I want to edit the files in my SD card using my computer, Ubuntu 14.04. However, when I insert the SD card, the Ubuntu cannot mount the Xbian partition, and gives ...
2
votes
0answers
128 views

Restore Btrfs snapshot from subdirectory to parent

I have a Btrfs partition which has a single subvolume at the top level (/root). It has subvol=root option in /etc/fstab. Every week, I take a readonly snapshot into /root/snapshots/... using: btrfs ...
0
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1answer
125 views

Filesystems not mounting on boot?

I'm getting this error after rebooting: Scanning for Btrfs filesystems * Stopping Read required files in advance [ OK ] * Starting Mount filesystems on boot ...
0
votes
1answer
221 views

Mounting failed - invalid argument

I've setup a Kali Linux installation on an SD card and created an encrypted LUKS partition with a LVM logical volume inside of it, then created a BTRFS filesystem inside. Almost everything works, but ...