Why OSD report error "symlink exists but target unusable: (2) No such file or directory" for block.db in RHCS ?

Issue

• How harmful IO errors associated with OSD block.db ?

  Mar 12 03:44:55 rhcsnode01 ceph-osd: 2020-03-12 03:44:55.894291 7fa02388c700 -1 bdev(0x55a1b3ad1800 /var/lib/ceph/osd/ceph-111/block.db) direct_read_unaligned 0x325c4023e~fc5 error: (5) Input/output error
  Mar 12 03:44:55 rhcsnode01 ceph-osd: /builddir/build/BUILD/ceph-12.2.8/src/os/bluestore/KernelDevice.cc: In function 'void KernelDevice::_aio_thread()' thread 7fa027ff8700 time 2020-03-12 03:44:55.894307
  Mar 12 03:44:55 rhcsnode01 ceph-osd: /builddir/build/BUILD/ceph-12.2.8/src/os/bluestore/KernelDevice.cc: 392: FAILED assert(0 == "got unexpected error from aio_t::get_return_value. " "This may suggest HW issue. Please check your dmesg!")