# dd if=/dev/rbd0 of=/dev/zero bs=1M
dd: reading `/dev/rbd0': Input/output error
1104+0 records in
1104+0 records out
1157627904 bytes (1.2 GB) copied, 0.253979 s, 4.6 GB/s
zsh: exit 1     dd if=/dev/rbd0 of=/dev/zero bs=1M
# dmesg
[509307.830921] end_request: I/O error, dev rbd0, sector 2260992
[509307.834828] Buffer I/O error on device rbd0, logical block 282624