OK, it is reproducible - I have a filserver with 6x 3TB in a BTRFS RAID 1+0 configuration.
From a client (and using NFS) I copy a 95GB tar file from the fileserver to a USB HD.
It seems at the very end (when BTRFS deletes the 95GB file on the server it falls over - btrfs-transaction and btrfs-flush_del using 3 to 5 cores at 50 to 100%.
OK, it is reproducible - I have a filserver with 6x 3TB in a BTRFS RAID 1+0 configuration.
From a client (and using NFS) I copy a 95GB tar file from the fileserver to a USB HD.
It seems at the very end (when BTRFS deletes the 95GB file on the server it falls over - btrfs-transaction and btrfs-flush_del using 3 to 5 cores at 50 to 100%.