Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: If I install 4 x 4TB drives on this unit and connect it to my computer, I see 4 new USB hdds in my PC or just one big drive?.
Document: You can install from 1 to 4 drives. I would leave the front door off until everything is working because it is difficult to work with. If you do have trouble getting it to open I would suggest a suction cup or scrap of Velcro to open it easily.The new computer had Windows 7 and a USB 3.0 port. I plugged in the ProBox, attached, the provided USB 3.0 cord and made sure the switch was set to USB.
If you are planning on running it on USB2, it seems solid thus far, and faster than some of the other options. (I'm averaging 40MB/sec reading off a 2tb drive onto one of my internals. Total of 1.7tb copy. )My experience with USB3 was the system dropping connect every 5 minutes or less. This is to a PC running a fresh install of win7 pro 64bit, with USB3 ports confirmed working on other devices.
This is a simple to use HDD enclosure, truly just plug and play. I am using it with 4 x 4TB drives for a total of 16TB of storage space. The controls are straightforward and easy to use. It's connected to a Macmini 6,1 and is running at USB 3.0 speeds. Here is a benchmark of the speed to verify: [...]The drives are setup in a software RAID 0 configuration.
I very rarely write reviews, so please believe me when I say that this Mediasonic HF2-SU3S2 4 bay hard drive enclosure is what we in the IT industry call 'a cheap piece of crap'. It's a technical term.This product did not work consistently with either ESata or USB 3.0 on my PC. It would see some drives, then not see them. It would stop working and freeze my pc. It would cause my pc to hang on shutdown. And the list goes on.
At first it came to life and then shut itself off. Looking at the indicators on the front of the box told me it was trying to connect using USB so I restarted and changed the connection method by holding the eSATA button selection. Once I did that it connected immediately and has been running flawlessly ever since.Since the drives were new each one had to be formatted. Once that was done the drives showed up in Windows Explorer just like any internal drive would show.
Edit: June 26, 2014. Added a star for the customer service. They reached out via this review's comments and orchestrated a unit swap. Whether it works or not remains to be seen, but that effort deserves an increase in rating.Original Review:I bought a Promise Pegasus R6 RAID sometime ago. As I filled that one up with 6-4TB drives, I was left with 6-1TB relatively new RAID ready drives.
I first used this enclosure with a three year old PC - worked flawlessly connecting via both eSATA and USB 3.0I was wondering if it would be the same on iMac - couldn't find consistent information online so I just decided to test it out for myself. Connected to the USB 3.0 on a brand new iMac 27" (purchased in June 2013) and.. voila! Works perfectly fine, iMac can see all drives without any problem.
Good concept, apparently poor execution. The unit is well built but in three attempts (this is the third unit I have purchase), I have not been able to get one to work. The Windows 8 PC does not &#34;see&#34; the drives in Windows Explorer although it does in Device Manager. No hep from the company online FAQs and they do not respond to e-mail queries on the functioning. Expensive frustration.
I have found this Hard Drive enclosure to be problematic. It generally only recognizes the hard disk in the drive 1 position and not the other installed drives. The drives generally require multiple attempts in order to get them to seat properly,  The user information for the unit is sparce at best. If I reboot my computer the unit turns off and has to be manually started. Perhaps I have missed the big picture on this unit, but it has not been a very useful addition to my computer.
Took the USB off the NAS, connected the ProBox 4 to a PC, found and formatted the new drive (Hardest part of this? - Finding the Win7 Disk manager! ), then re-connected the ProBox 4to the NAS, and there was my new drive. The ProBox 4 costs about as much as a single disk drive, and it was quite painless to get up and running. Overall, I find the Mediasonic HF2-SU3S2 ProBox 4 to be a well built and reasonably priced storage solution.
Answer: You will see 4 drives.