No available diskspace - but admin page reports 1 tb free

I had this filled up disc deleted about 2TB then had disk full messages. There is a thread which also describes this issue and the solution but i cannot find it

Thanks to mdgm for the actual solution

You have to do a balance. This is possible through Frontview" System -Settings- Volume Settings

I did it through SSH as I did not seem to fix it this way and this is my cheat sheet
1) Get % space used on NAS

	# df - h data

Result similar to /devNNN X.XTb Y.YTb ZZZGb A%
2) Get space used on NAS devices

	# btrfs fi show

optional

	# btrfs fi df /data

3) run balance

	# btrfs balance start /data -dusage=%

where % is A% from step 1, only use number do not put in % sign
window will hang till finished
4) follow progress in second instance of putty with

	# btrfs balance status -v  /data

where -v is optional

5) when finished check using step 2

It seem that the space despite being "Free" is still allocated as used, a balance "frees" up this space again

davexyz wrote:
This is possible through Frontview" System -Settings- Volume Settings

Volume Schedule. Currently a balance can only be run from the UI on a schedule. Though of course you can schedule it, let it run then disable the schedule again if you wish.

davexyz wrote:
optional # btrfs fi df /data

Actually you need this along with the previous command to confirm whether a balance is what is needed.

Or you could download the logs and look at btrfs.log

davexyz wrote:
3) run balance # btrfs balance start /data -dusage=%

You can do e.g.

# btrfs balance start /data -dusage=25 &

Note the &. Then you don't need to open a second window

Thanks for your reply

The scheduled Balance from frontview didn't make any difference.

I'm not very familiar with SSH, so could one of you confirm that its a "balance" I need to run ?

The first suggested command seems to fail:

# df - h data
df: `-': No such file or directory
df: `h': No such file or directory
df: `data': No such file or directory
df: no file systems processed

# btrfs fi show
Label: '0e369e88:data'  uuid: 27b2903d-10d7-44d7-a9d5-44c45edda69b
        Total devices 1 FS bytes used 1.48TiB
        devid    1 size 2.72TiB used 2.72TiB path /dev/md127

# btrfs fi df /data
Data, single: total=2.72TiB, used=1.48TiB
System, DUP: total=8.00MiB, used=352.00KiB
System, single: total=4.00MiB, used=0.00B
Metadata, DUP: total=1.00GiB, used=766.41MiB
Metadata, single: total=8.00MiB, used=0.00B

The first one should be

# df -h

See this line

yesbor wrote:
Metadata, DUP: total=1.00GiB, used=766.41MiB

The metadata should have 0.5GiB free but more space could not be allocated to it as space has been allocated to data.

Do you have a backup?

You might need to add more space to be able to run a balance in this situation.

After deleting som files bringing up available free space for metadata I ran the scheduled Balance from frontview.

...and it did the trick

# btrfs fi df /data
Data, single: total=1.21TiB, used=1.19TiB
System, DUP: total=32.00MiB, used=192.00KiB
System, single: total=4.00MiB, used=0.00B
Metadata, DUP: total=1.00GiB, used=439.41MiB

# btrfs fi show
Label: '0e369e88:data'  uuid: 27b2903d-10d7-44d7-a9d5-44c45edda69b
        Total devices 1 FS bytes used 1.19TiB
        devid    1 size 2.72TiB used 1.21TiB path /dev/md127

Thank you mdgm for your quick and helpful reply.

This also worked for me, after about 300GB free space went missing.

Before:

# btrfs fi show
Label: '0e357b14:data'  uuid: 34bda540-18c4-4437-b708-f7d6d81b53c3
	Total devices 1 FS bytes used 5.13TiB
	devid    1 size 5.45TiB used 5.45TiB path /dev/md127

After:

# btrfs fi show
Label: '0e357b14:data'  uuid: 34bda540-18c4-4437-b708-f7d6d81b53c3
	Total devices 1 FS bytes used 5.13TiB
	devid    1 size 5.45TiB used 5.19TiB path /dev/md127