>>103148753
# mount /dev/sdb1 /somedir
...: can't read superblock on /dev/sdb1.
dmesg(1) may have more information after failed mount system call.
# dmesg -H
[Nov11 21:33] EXT4-fs (sdb1): mounted filesystem UUID r/w with ordered data mode. Quota mode: none.
[ +0.000794] EXT4-fs (sdb1): unmounting filesystem UUID
# fsck /dev/sdb1
/dev/sdb1: clean, 22/31260672 files, 27397114/125026560 blocks
What is happening?