The MediaVault MVHD-500 comprises an enclosure with a UL Class 125 fire rating and dual Seagate Momentous 5400.4, 2.5", 250 GB SATA-300 hard drives. The Seagate drives arrive in their own NexStar 3 SATA/USB enclosures, which was a pleasant surprise for me as I have used the NexStar enclosures in the past and think they are great. The 5400 RPM drives have 8 MB buffers, <12 ms average seek times, 5.6 ms latency, and a transfer rate of 300 MBps. The external transfer rate, however, is limited by the USB bus to 58 Mbps.

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Interestingly, I found that the separate internal drive enclosures connected to separate USB cables, and from there to two separate external USB ports. This, of course, required two USB cables to connect to the PC and two USB ports as well--unless you have a USB hub. Also, since the drives use power from the USB connection, you may find that some systems with low USB power have problems, and FireKing strongly suggests the use of their provided cables. I do have a powered USB hub, and that neatly solves the problems of sufficient power and tying up a 2nd USB port.I would recommend for you to use a powered USB hub as well. I suppose I expected either a 500 GB drive or some RAID interface presenting the storage as a single drive, but that's not the case. If you're using backup software such as the software provided by MediaVault, there should not be an issue with storage transparently spanning two drives, but I do find that a potential concern. The pro's are, you can have two separate backup destinations and don't rely on a software interface, whether backup or RAID to access your data, the con's are that you really have two 250 GB destinations and not a 500 GB volume.