Mediasonic HFR2-SU3S2 PRORAID 4 Bay 3.5" SATA Hard Drive Enclosure - USB 3.0 & eSATA

This is a beautifully engineered product that simplifies the installation and operation of a complex sub-system delivering astonishing price-performance.I recently upgrade the RAID 10 storage on my workstation system (Supermicro 5036T-T) to use use 954GB SanDisk X400 SSDs instead of WD 10KRPM HDDs. So what am I going to do with four of these replaced high-performance mechanical drives? Why not put them in an external array enclosure? That's when I bought the Mediasonic HFR2-SU3S PRORAID 4-Bay enclosure.DO NOT CONFUSE this on-board RAID controller model with the similar looking ProBox HF2-SU3S2 which uses a port multiplier to attach 4 drives to a PC through a single data transfer connection. Here's why: with the on-board RAID controller, the OS issues a single read or write IO operation through the cable to the external PRORAID box which then takes care of managing the multiple RAID operations which requires at least 4 IOs to the independent disks. With the less sophisticated ProBox unit, the PC must issue at least 4 IOs through the cable--one for each disk (this is all hidden from the applications and user, of course). Even though the unit uses FIS multiplexing to initiate parallel operations, the individual disks maintain their identities and therefore reduce the throughput of the external cable by 4.This is a carefully engineered and designed product, BUT YOU NEED TO READ THE DIRECTIONS CAREFULLY (!!!!!!!!!!!) BEFORE installation. There are a number of steps that must be followed, but the directions are clearly written with useful illustrations (and in proper English). There are so many well designed aspects that aid the end user that it could make a review three times as long (when I say design, I don't mean just the visual aesthetics but overall systems design including hardware--mechanical and electronic--software, and integration--this is a fully functioning independent sub-system--and documentation).The buttons, indicators and labels are all obviously carefully considered. Note: there is a hidden button on the back of the unit behind a cover that must be opened and used to complete setup of the RAID. This design prevents the inadvertent changing of the RAID type which would cause the accidental loss of data. This interlock does, however, provide an extra but useful step that could confuse the someone if they do not READ THE INSTRUCTIONS CAREFULLY AND FULLY BEFORE BEGINNING. I write this advice not because the instructions are confusing--quite the opposite--but because this is a sophisticated product that requires several levels of configuration in order to set up the physical and logical structures required to integrate seamlessly with the OS. I don't know how they could have made this easier--it is very well done. There are a lot of great features that I could write about now, but I suspect it is a level of detail that would make this review less readable. I think I can summarize that by borrowing a term from the digital camera market: this is clearly a Prosumer (professional/consumer hybrid) product that is nearly commercial in its quality, but accessible to the consumer market.So, one more potentially interesting observation. This unit offers two types of external cable connects between the computer system and the external RAID: USB 3 and eSATA 3Gbps. On the box is clearly displayed that USB 3 transfers at up to 5Gbps and eSATA up to 3Gbps. However, transfer speed IS NOT THE SAME as throughput which is the effective overall transfer rate end-to-end including delays in media arbitration, the OS system functions, and various other components incurred as a result of initiating the large number of operations usually required to complete actual the data transfers encountered during system operation. As a result, I tested both link interfaces using a simple test: repeatedly copying a 2.2GB file from the PC's SSD to the empty external logical drive created on the PRORAID unit.(Full disclosure: these results may have been influenced by the controllers through which the transfers took place. The USB 3. is connected through a Renesas Electronics PCI-e Host controller, and eSATA is connected through an IOCREST (SiI3124) PCI-X controller.) Overall, the slower rated eSATA link has considerably higher write throughput of 314 MB/s compared to the USB link with a throughput of 110 MB/s. This was a convenient test to run because access to the PRORAID storage is transparent to the link type. All I needed to do was switch the cables. How nice is that?!

These enclosures are amazing little devices - - and I come from a systems engineering background where we deployed storage racks costing in the hundreds of thousands of dollars.I've just replaced one of these that has spun pretty much without rest for 11 years. I'm replacing it not because it failed, but because I was starting to think it was running on borrowed time. And, I wanted to attach the new unit to a faster SATA III interface. I'll use the old one elsewhere.The previous unit ran 4 Western Digital "Black" drives, 1Tb each, in RAID5 configuration, and none failed, so I can't speak to how well these work in rebuild mode. I've read that they do fine. Really, for the money, I don't see how you can do better than these. If you use a decent-quality eSATA card, setup is a breeze. I've always trusted StarTech and have set the new unit up on a two-port eSATA III card.

I'm running a NAS with one 16TB drive and three 12TB drives in a hybrid RAID 5. I needed a better backup system and didn't see adding another NAS as being cost effective. I've attached this via USB 3.0 to a Windows PC. Without a raid, Windows will see the each drive in the closure as a separate drive. You cannot expand a volume in Windows across multiple USB attached drives. You can purchase software to run in Windows that will do this, but none of the free applications do this function. I've got two 6TB drives and one 12TB drive installed in the 4 bay RAID version of these Mediasonic enclosures. RAID 0 (spanning) is setup in the enclosure so Windows sees a single 24TB volume. Worth noting, RAID 0 in any device will not have drive fault tolerance (plenty of other RAID options in this enclosure). Since it's a backup to a fault tolerant NAS, I didn't need redundant redundancy ;). I've completed the backups to this enclosure which moved a bit over 14TB and it took about 30 hours (normal). When the PC is powered off, the enclosure goes into standby. As far as sleep, maybe this is what they're talking about, maybe it's not. While I'm using it as a backup in RAID 0, I could easily see using this as budget server storage in RAID 5 attached to a decently powerful PC.As the headline states, I'm impressed. I've attached an image of my home system as a resume of sorts, so you know this isn't my first rodeo. This Mediasonic 4 bay RAID enclosure performs the functions I needed and does it very well. Most notably is how quiet the fan runs. I actually bought the Cenmate 4 Bay RAID Hard Drive Enclosure first. Hours after I finished the backup, I was hoping the fan would slow and quiet down since the drives weren't spinning. They didn't and I repacked the enclosure to return it. The fan on that box is unnerving. I'm not a fussy guy, but the fan in the Cenmate was just too much for me.