A data de-duplication approach leverages acceleration hardware in SSDs for performing digest computations used in de-duplication operations and support on behalf of an attached host, thereby relieving the host from the computing burden of the digest computation in de-duplication processing. The butt end male-female coupling means have respective and mating cam-type ends able to cooperate through interference in the butt-wise coupling of two adjacent panels. The surveillance routine checks to see if it has enough time for the service processor to respond to its previous probe. The magnetic member serves to apply a magnetic attraction force to a shaft of the fan structure to make the shaft quickly restore to its optimal operation position so as to reduce wear and lower the noises and vibration of the fan structure in operation.