Re: BTRF: no free space

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2023/10/22 21:13, Reindl Harald wrote:
> this is a *new* filesystem and somewhere in the middle of the night at
> 10% usage a large rsync stopped because BTRF thinks the filesystem is
> full - how is this possible in 2023?
>
> Metadata, DUP: total=1.00GiB, used=945.61MiB

Metadata is already exhausted.

Thus no way to start balance.

>
> -----------------
>
> defaults,noatime,compress-force=zstd:15,ssd,ssd_spread,nodiscard,nobarrier,noexec,nosuid,nodev,commit=60
>
> adding "clear_cache" which solved such issues in the past eve refuses to
> mount it
>
> [root@arrakisvm:~]$ mount /mnt/fileserver-backup/
> mount: /mnt/fileserver-backup: mount(2) system call failed: No space
> left on device.
>
> -----------------
>
> [root@arrakisvm:~]$ df
> Filesystem     Type   Size  Used Avail Use% Mounted on
> /dev/sdd1      btrfs  2.0T  209G     0 100% /mnt/fileserver-backup
>
> [root@arrakisvm:~]$ btrfs fi df /mnt/fileserver-backup
> Data, single: total=1.95TiB, used=207.05GiB

Is this after you deleted some files? Or exactly where the situation is
when the ENOSPC happens?

If it's the latter case, it looks like a kernel bug that we're
over-allocating data chunks, and we need to investigate.
But please provide the initial 'btrfs fi df' output for that case.

If it's the former case and you're trying to make up enough space, I'm
afraid you have to delete more data until one continous 1G chunk is
freed up, then you can do balance to free up most of the space.

Thanks,
Qu

> System, DUP: total=8.00MiB, used=224.00KiB
> Metadata, DUP: total=1.00GiB, used=945.61MiB
> GlobalReserve, single: total=512.00MiB, used=0.00B
>
> [root@arrakisvm:~]$ btrfs balance start -dusage=5 /mnt/fileserver-backup
> ERROR: error during balancing '/mnt/fileserver-backup': No space left on
> device
>
> [root@arrakisvm:~]$ dmesg
> [Sun Oct 22 12:31:52 2023] BTRFS info (device sdd1): balance: start
> -dusage=5
> [Sun Oct 22 12:31:54 2023] BTRFS info (device sdd1): 496 enospc errors
> during balance
> [Sun Oct 22 12:31:54 2023] BTRFS info (device sdd1): balance: ended with
> status: -28
>
>