A race condition between tier migration and hard link creation results in the hard link operation failing with a 'File exists' error, and logging 'Stale file handle' messages on the client. This does not impact functionality, and file access works as expected.
This race occurs when a file is migrated to the cold tier after a hard link has been created on the cold tier, but before a hard link is created to the data on the hot tier. In this situation, the attempt to create a hard link on the hot tier fails. However, because the migration converts the hard link on the cold tier to a data file, and a hard link to the file already exists on the cold tier, the links exist and work as expected.