Symptom
tail when used on v6.5+ platforms will successfully open a file, but elicit a warning similar to:
tail: unrecognized file system type 0x794c7630 for ‘error_log’. please report this to bug-coreutils@gnu.org. reverting to polling
Cause
Older versions of tail, such as shipped with RHEL7.2, do not ship with a version of coreutils that properly detects the magic number for OverlayFS.
Solution
Ignore it. This is pending on an upstream vendor patch in coreutils, which patched already.