DM4LH Direct Attached Storage, 4 Drive Capacity Hardware RAID Solution (Diskless)

I bought this unit when it was selling for $50, thinking that if it didn't work, I'd at least have 4 new hd's that I could try in something else.I'm glad I took the chance!This unit looks to be a model that's 2-3 years old. I believe it's a rebranded Onnto dataTale RC-M4DJ. It only has USB 2.0 and eSata. The newer models are USB 3.0 (and cost much more).The rail system for the hd's is pretty nifty. Definitely made it easy to line up the drives with the connections. The only issue was that it was a bit of a snug fit at the top, so you need to be careful not to push too hard, otherwise you could end up slamming it into the other end.The specs say that 4 2TB drives can be used. I set the unit up with 4 1TB drives (WD Blue 1TB 64MB cache) in RAID 5 mode.FYI - RAID 5 with 4 drives gives about 75% usable space with a 3x read speed gain.RAID 5 with only 3 drives (keeping the 4th as a hot spare) gives about 66% usable space and 2x read speed gain.I setup the unit using the included Windows software (built the RAID in Windows, formatted in Ubuntu). The software was a bit utilitarian looking, but it did the job and I only had to use it once. The software did have options for setting up hot spares, automatic rebuilds, unit idle/standby time, etc. I don't think all those options are accessible through the unit's front panel.I have the unit hooked up to a Linux/Ubuntu 14.04.1 box via eSata, formatted in ext4. I didn't have to find any special drivers -- it just worked. The speed is very fast. Write speeds using dd show in the 350 MB range, which comes out to about 2.8 Gb which is close to what eSata's specs are. Read speeds are in the same range or *sometimes higher*. I'm a little skeptical as those numbers are close to the theoretical limit. So either my testing was invalid (which it could be), or the 64MB buffer on the hd's are giving the transfer a boost, or maybe the eSata interface in the unit is SATA 6G (the pc does have that). I did a very large (1.7GB) file over my network and Windows was reporting about 113 MB/s (0.9 Gb) transfer rate. My network is 1Gb so if the unit was really as fast as indicated, then it would make sense that the network would be the bottleneck. YMMV. In any case, it's fast enough for what I'm using it for -- backups and media storage.Just to be clear, this isn't a NAS (network attached storage). It is Direct Attached Storage so you'll need to hook it up to a pc. You won't get the newest technology like USB 3.0 and support for really large drives, but it does do RAID and it's performs very well. For the money, it's a really good buy.

Great value. I was originally disappointed at write speed on external esata (Dell T7500) was about 75 MB/sec in raid 5. I recently updated Dell driver and now am seeing 150 MB transfer as originally expected. Documentation that comes with enclosure claims to run raid 5 w/spare but found no menu setting on enclosure for this raid 50.

Works well so far...nice design, holds up to 4 drives.

Very nice, easy to use and directions are clear.