The problem was that the optimize method of the ARCHIVE storage
engine was not preserving the FRM embedded in the ARZ file when
rewriting the ARZ file for optimization. The ARCHIVE engine stores
the FRM in the ARZ file so it can be transferred from machine to
machine without also copying the FRM -- the engine restores the
embedded FRM during discovery.

The solution is to copy over the FRM when rewriting the ARZ file.
In addition, some initial error checking is performed to ensure
garbage is not copied over.