CK wrote in his review that it μ.u 2 models with different cache sizes are from TrekStor DataStation maxi, of which in this variant a WD drive is to be installed and in the other, more expensive variant, a Samsung drive. I can not confirm:
The 'official' distinction of both models is that the slightly more expensive model includes an S-ATA hard drive (Model no. DSMMU-S-SUA), while this model (Model no. DSMMU-P-INA) internally with IDE ( P-ATA) is working. For me, however, lies not Western Digital - drive with 8 MB cache in the housing, but a Seagate Barracuda 7200.9 with IDE interface and (in spite of the name of Amazon) 16 MB cache. TrekStor DataStation installed in this so apparently different plates. The time now is anyone's guess what would have been a better choice ...