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#1 2020-01-01 18:33:57

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Hello everyone, hopefully someone can point me in the right direction on how to fix and prevent in the future. Basically a BTRFS states that there is no more space left. Currently running a full balance just to see if it helps as it is mentioned in both btrfs wiki, arch wiki and others which helped temporarily. after a couple days, the same issue cropped up again. How do I get btrfs to stop running out of space. running balance every time is not really an option as it takes forever and partial balance doesn't seem to help only full balance of both data and metadata helped so far, but only temporary. Never had this problem with btrfs before and not sure what's causing it.

Background
  1. Installed a new 10TB drive (Seagate) - /dev/sda)/

  2. Created 40 GB Swap - /dev/sda1

  3. Created 10TB btrfs - /dev/sda2

  4. Updated fstab (auto-mount files on boot)

  5. Turned on Swap

  6. Mounted btrfs to /files/

  7. copy all files from old drive (mounted to /home/user/tmp_drive/ via usb SATA adapter

  8. Reboot

  9. Use handbrake to encode a movie, disk all of a sudden btrfs has no more space.

  10. Run btrfs balance start /files/ in progress

Note: no snapshots enabled

General BTRFS Information

btrfs fi usage /files

sudo btrfs fi usage /files :
Overall:
    Device size:		   9.05TiB
    Device allocated:		   2.42TiB
    Device unallocated:		   6.63TiB
    Device missing:		     0.00B
    Used:			   2.40TiB
    Free (estimated):		   6.65TiB	(min: 3.33TiB)
    Data ratio:			      1.00
    Metadata ratio:		      2.00
    Global reserve:		 512.00MiB	(used: 0.00B)

Data,single: Size:2.41TiB, Used:2.40TiB (99.35%)
   /dev/sda2	   2.41TiB

Metadata,DUP: Size:3.00GiB, Used:2.75GiB (91.61%)
   /dev/sda2	   6.00GiB

System,DUP: Size:8.00MiB, Used:288.00KiB (3.52%)
   /dev/sda2	  16.00MiB

Unallocated:
   /dev/sda2	   6.63TiB

btrfs fi show

sudo btrfs fi show
Label: none  uuid: 503e1c5b-5d41-4e6a-8ef5-75678c730bc7
	Total devices 1 FS bytes used 2.40TiB
	devid    1 size 9.05TiB used 2.42TiB path /dev/sda2

btrfs fi df /files/

sudo btrfs fi df /files/
Data, single: total=2.41TiB, used=2.40TiB
System, DUP: total=8.00MiB, used=304.00KiB
Metadata, DUP: total=3.00GiB, used=2.74GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

btrfs subvolume show /files

sudo btrfs subvolume show /files/
/
	Name: 			<FS_TREE>
	UUID: 			c745d61b-ab32-4fcf-b0a5-7f0b522f3fd3
	Parent UUID: 		-
	Received UUID: 		-
	Creation time: 		2019-12-27 16:40:38 -0700
	Subvolume ID: 		5
	Generation: 		6621
	Gen at creation: 	0
	Parent ID: 		0
	Top level ID: 		0
	Flags: 			-
	Snapshot(s):

fstab

# /dev/nvme0n1p4
UUID=e1922aed-d337-47e6-a979-2f72f49e1a99       /               ext4            rw,noatime      0 1


# /dev/nvme0n1p2
UUID=884926e4-f13d-40f0-9cea-c8868a62b2a7       /boot           ext4            rw,noatime,data=ordered 0 2

# /dev/nvme0n1p1
UUID=2172-5FFB          /boot/efi       vfat            rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro       0 2

# /dev/nvme0n1p3
UUID=fc2a2e02-2d82-4214-b5ec-fa5e14d4f038       /home           ext4            rw,noatime,data=ordered 0 2

# /dev/nvme1n1p9
UUID=cc7c9dcb-8bf3-4490-8c86-115c524f473e       /var            ext4            rw,noatime,data=ordered 0 2

# /dev/sdc2
UUID=503e1c5b-5d41-4e6a-8ef5-75678c730bc7       /files          btrfs           rw,nosuid,nodev,relatime,space_cache,subvolid=5,subvol=/        0 0

# /dev/sda1
UUID=9ff1a32a-36bf-4dff-9663-c1dcaaafbc0f       none            swap            defaults        0 0
Second Day

sudo btrfs fi usage /files

sudo btrfs fi usage /files
Overall:
    Device size:		   9.05TiB
    Device allocated:		   2.56TiB
    Device unallocated:		   6.49TiB
    Device missing:		     0.00B
    Used:			   2.55TiB
    Free (estimated):		   6.49TiB	(min: 3.25TiB)
    Data ratio:			      1.00
    Metadata ratio:		      2.00
    Global reserve:		 512.00MiB	(used: 0.00B)

Data,single: Size:2.56TiB, Used:2.55TiB (99.65%)
   /dev/sda2	   2.56TiB

Metadata,DUP: Size:3.00GiB, Used:2.76GiB (92.08%)
   /dev/sda2	   6.00GiB

System,DUP: Size:32.00MiB, Used:304.00KiB (0.93%)
   /dev/sda2	  64.00MiB

Unallocated:
   /dev/sda2	   6.49TiB

sudo btrfs fi df /files

sudo btrfs fi df /files/
Data, single: total=2.56TiB, used=2.55TiB
System, DUP: total=32.00MiB, used=304.00KiB
Metadata, DUP: total=3.00GiB, used=2.76GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

sudo btrfs fi show

sudo btrfs fi show
Label: none  uuid: 503e1c5b-5d41-4e6a-8ef5-75678c730bc7
	Total devices 1 FS bytes used 2.55TiB
	devid    1 size 9.05TiB used 2.56TiB path /dev/sda2

df -h

df -h
Filesystem      Size  Used Avail Use% Mounted on
dev              16G     0   16G   0% /dev
run              16G  2.1M   16G   1% /run
/dev/nvme1n1p4  138G   12G  120G   9% /
tmpfs            16G   53M   16G   1% /dev/shm
tmpfs            16G     0   16G   0% /sys/fs/cgroup
tmpfs            16G  143M   16G   1% /tmp
/dev/nvme1n1p2  2.0G   85M  1.8G   5% /boot
/dev/nvme1n1p9  209G   15G  184G   8% /var
/dev/nvme0n1p1  865G  153G  668G  19% /home
/dev/nvme1n1p1  286M  121M  165M  43% /boot/efi
/dev/sda2       9.1T  2.6T     0 100% /files
tmpfs           3.2G   18M  3.2G   1% /run/user/1000
/dev/sr0         91G   91G     0 100% /run/media/yevsey/APOCALYPSE_NOW_FINAL_CUT

Last edited by krutoileshii (2020-01-01 18:54:51)

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#2 2020-01-01 19:26:32

mxfm
Member
Registered: 2015-10-23
Posts: 141

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

It seems like a bug in BTRFS. AFAIK, there are patches and this issue likely to be fixed in next kernel releases.

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#3 2020-01-01 21:01:11

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Definitely seems like it. Do you by chance know which kernel version has the patches? I was going to compile it and give it a shot.

mxfm wrote:

It seems like a bug in BTRFS. AFAIK, there are patches and this issue likely to be fixed in next kernel releases.

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#4 2020-01-01 23:05:31

loqs
Member
Registered: 2014-03-06
Posts: 9,601

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

You could try linux 5.5-rc4 available using the linux-mainline package from AUR and Unofficial_user_repositories#miffe.

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#5 2020-01-01 23:39:50

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

5.5-rc4 doesn't have the patch just yet. Doesn't look like it's been accepted just yet, I'm going to give it a week or so and if its still not in, just patch it manually and test. Since it only really causes issues with user-space and not actual data, i can way since everything is backed up anyway.

Patchwork status

loqs wrote:

You could try linux 5.5-rc4 available using the linux-mainline package from AUR and Unofficial_user_repositories#miffe.

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#6 2020-01-02 00:03:13

ronmon
Member
Registered: 2011-04-15
Posts: 40

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Did you partition it with fdisk or gdisk?

/dev/sdf1       3.7T  1.9T  1.8T  53% /media/4x2
/dev/sda1       2.8T  1.2T  1.6T  42% /media/backup2
/dev/sdd1       3.7T  1.9T  1.8T  53% /media/tv
/dev/sdb1       2.8T  1.1T  1.7T  41% /home
/dev/sde1       3.7T  1.8T  2.0T  48% /media/4x1

I don't have any 10TB, but several larger than 2.4. Those are all btrfs.

Not sure if it's relevant, just a guess.

Last edited by ronmon (2020-01-02 00:11:53)

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#7 2020-01-02 00:11:11

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Partitioned with gparted actually. But that's not the issue as i have anothe PC with same kernel version that was partitioned with gdisk exhibiting the same issue. currently in the middle of compiling the mainline with the above patch included manually to test it out. With all of the modules it compiles, even on 16 cores it's taking a bit of time. Once I get a chance to test it, i will report back which might be a few days as I have to write quite a bit to disk before it manifests itself.

btrfs utilities do show the correct size and available space, its the df that is getting an incorrect free space which causes issues until metadata is rebalanced again.

what kernel version are you on btw? I'm on 5.4.6 , which is where I started to see the issues. This wasn't there before.

sudo gdisk -l /dev/sda
GPT fdisk (gdisk) version 1.0.4

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 19532873728 sectors, 9.1 TiB
Model: ST10000VN0004-1Z
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): CBA08A5C-9491-42D2-9FB6-9884D52DE9A0
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 19532873694
Partitions will be aligned on 2048-sector boundaries
Total free space is 4029 sectors (2.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048        97656831   46.6 GiB    8200  
   2        97656832     19532871679   9.0 TiB     8300  
ronmon wrote:

Did you partition it with fdisk or gdisk?

Last edited by krutoileshii (2020-01-02 00:15:51)

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#8 2020-01-02 00:35:09

ratcheer
Member
Registered: 2011-10-09
Posts: 699

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Use:

btrfs balance start -v -dusage=85 /files

If you let it default to 100%, it will run forever.

If it fails with 85, try something like 40, then 60, then 85.

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#9 2020-01-02 00:42:14

loqs
Member
Registered: 2014-03-06
Posts: 9,601

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

krutoileshii wrote:

what kernel version are you on btw? I'm on 5.4.6 , which is where I started to see the issues. This wasn't there before.

Not seeing any btrfs changes in 5.4.6 or 5.4.5 there were some in 5.4.45.4.7 also contains some btrfs changes.

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#10 2020-01-02 01:22:42

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

I've used that but unfortunately nothing below 95 currently makes a difference which with 2.6tb of data takes a while. Finished compiling the kernel with the patch though so will give it a shot once this round of balancing finishes.

ratcheer wrote:

Use:

btrfs balance start -v -dusage=85 /files

If you let it default to 100%, it will run forever.

If it fails with 85, try something like 40, then 60, then 85.

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#11 2020-01-02 03:55:37

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Also, looks like similar issues that started at around 5.4.1 mailing list discussion

P.S. still running balance.. since metadata seems to be the issue might try to just balance that, should be faster.

loqs wrote:
krutoileshii wrote:

what kernel version are you on btw? I'm on 5.4.6 , which is where I started to see the issues. This wasn't there before.

Not seeing any btrfs changes in 5.4.6 or 5.4.5 there were some in 5.4.45.4.7 also contains some btrfs changes.

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#12 2020-01-02 12:48:22

loqs
Member
Registered: 2014-03-06
Posts: 9,601

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

krutoileshii wrote:

Also, looks like similar issues that started at around 5.4.1 mailing list discussion

5.4.1,  perhaps the issue was introduced with 5.4.

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#13 2020-01-03 03:35:03

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Quick update: booted into parched mainline 5.5-rc4. Wrote over 120GB with no issues, going to write another 120GB to see if it pops up. Patch seems promising, hopefully solves the issue and get backported.

Last edited by krutoileshii (2020-01-03 03:36:25)

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#14 2020-01-05 03:18:30

cmurf
Member
Registered: 2019-09-06
Posts: 14

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

You can revert to kernel 5.3.18 in the meantime, as a work around. The bug is actually more than one bug going back a while, but is exposed in 5.4 due to a new overcommit behavior for metadata. There are also patches you could apply if you prefer to use 5.4 series, but these patches may not be the final ones that'll be accepted for merge after testing.
https://patchwork.kernel.org/project/li … ies=208445

It's advised not to balance metadata, it can make the problem happen more often, and really shouldn't be necessary anyway. Explanation in this upstream post:
https://lore.kernel.org/linux-btrfs/CAN … ad03ca88f6

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#15 2020-01-05 18:23:36

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

The metadata part was interesting read. As for rolling back, I'll just use patched mainline until the fix makes it into the kernel. The fact that I wrote over 2.6Tb in under a week likely increased my chances of hitting the issue.

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#16 2020-01-13 13:10:57

onkehh
Member
Registered: 2014-10-03
Posts: 10

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Looks like my thread got redirected to this one - thanks all, I downgraded the kernel to 5.3.13.1 and ran a btrfs balance on the volume, all good so far. Will keep an eye out for when the patches hit stable release. Cheers,

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#17 2020-01-14 21:27:43

raneon
Member
Registered: 2013-11-02
Posts: 49

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Did run now twice into this issue after reinstalling 2 systems... But I fixed it by running "btrfs filesystem resize 1:max /home" and running btrfs scrub once. Not sure if  it was necessary to delete some files, but I tried this as well, so don't know what fixed it finally for me.

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#18 2020-01-15 02:53:58

krutoileshii
Member
Registered: 2019-01-15
Posts: 27

Re: BTRFS No More Free Space (10 TB Single Disk only 2.6TB used)

Quick Update: Currently sitting on 5.4.10 and haven't experienced any issues just yet. So far wrote about 400GB of data, but need to keep an eye on it for a bit more. Hopefully patches make it and get backported.

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