btrfs check -b -s 0 /dev/sdi2

[1/7] checking root items
[2/7] checking extents
[3/7] checking free space cache
failed to load free space cache for block group 9541332762624
failed to load free space cache for block group 9542406504448
...
failed to load free space cache for block group 19526876921856
failed to load free space cache for block group 19527950663680
[4/7] checking fs roots
[5/7] checking only csums items (without verifying data)
[6/7] checking root refs
[7/7] checking quota groups skipped (not enabled on this FS)
using SB copy 0, bytenr 65536
Opening filesystem to check...
Checking filesystem on /dev/sdi2
UUID: ae87b3cf-afa8-4a00-ac7a-6abb9e58d9ba
found 7899002138624 bytes used, no error found
total csum bytes: 7703426140
total tree bytes: 8988393472
total fs tree bytes: 440893440
total extent tree bytes: 129482752
btree space waste bytes: 677001276
file data blocks allocated: 110991598215168
 referenced 7888705048576