Currently mitigated by manually changing the upload folder when the issue arises in a slave. The issue is not destructive, files will be written to replicas without issue, but one replica may be unable to do so. Changing the upload directory on the replica resolves the issue. It would be ideal if the replicas could write millions of files without the filesystem getting crashed by them.
PHP issues a file permissions exception and the file cannot be written to. I am assuming that the file system gets issues with allocation and can't write to the directory (I do not understand the cause) . Regardless of how often we try or the permissions of the file. The files never happen to exist.
The issue is serious, but delicate and not fatal at all.