Pros: I just bought this drive yesterday and ran some benchmarks (on an SATA2 board): HD Tune: Read: 109.5 MB/s average, 144.0 MB/s max, 58.4 MB/s min. Read access time 19.7 ms Write: 106.8 MB/s average, 141.5 MB/s max, 56.5 MB/s min. Write Access time 17.8 ms As you can see, the access times are a bit slow (to be expected with a 5400 rpm drive), but the transfer rates are very decent due to the large data densities. The drive is very quiet, does not vibrate and stays cool - 31 degrees Celsius after 10 hours of surface scanning, ventilated by a slow 600 rpm fan. The drive's formatted capacity is approx. offers 3726 GB.

Cons: Obviously the drive is very expensive. I got it for $350 and free shipping. Which is a lot, but as 3TB drives also cost around $250 these days, the surcharge for having the largest capacity is not so bad. Neutral: -The drive probably uses advanced formatting with 4 KB sectors. -The drive is pretty heavy and thus probably a 5 platter design. 4 1TB platters would have been nicer, of course.

Overall Review: The other reviewer talking about the Hitachi GPT Disk Manager has misunderstood something. The drive works out of the box with 64 bit Windows systems that support GPT. In addition to that, Hitachi offers a drive manager to use the 4TB under for example 32bit Windows XP. I have not tried to use it under such an old operating system and probably would not recommend it. But driver manager is not a limitation of Hitachi, but an extra service they offer for users of old operating systems.

Pros: Very Large, Runs cool currently 31c, Works fine with windows x64 and as noted by other reviewer its not a slow drive either

Cons: Price I guess because the $/GB was higher then the Seagate XT 3TB and that drive was alot faster

Overall Review: I can't believe so many people have problems with formatting hard drives or getting the concept of formatting and losing space when you really aren't hard drives are sold in bytes but when you increase the measurement it is divided by 1024 each time not 1000 so for example this is a 4TB drive that's 4,000,000,000,000B=3,906,250,000KB=3,814,697MB=3725GB=3.63TB Formatted Looks like the hard drives are finally coming down in price again

Pros: Large and quiet.

Cons: I cannot find information or support about this drive on Hitachi's website.

Overall Review: The part number on the protective bag says "0S03364", but I cannot find that part number in Hitachi's website and does not match any number on the drive label. The serial number on the bag matches the one on the drive. The description on the bag says "Hitachi 3.5 4TB Coolspin IDK bulk pack - ww". One of the part numbers on the drive is 0F14696 and the other part number is H3D40003254SE and a similar looking model number is HDS5C4040ALE630. None of these show up on the Hitachi website. Also the Hitachi support tools do not work on drives over 2TB. This drive was made in November 2011 and has the coolspin logo on the label. It works as advertised but the lack of documentation and support tools make me reluctant to buy another one. Get with it Hitachi!

Pros: Read/Write is very high, 150MB/s+.

Cons: It started erroring out, I have to power the drive off then spin it back up for it to come back up.

Pros: Capacity (Large)

Cons: Reliability (Poor)

Overall Review: Purchased through NewEgg and have had in service since March. Started getting various errors beginning in June (less than 4 months) using this drive as a backup target (64-bit Win7 Ultimate). Eventually ran CHKDSK /F to have it find and correct(?) a single failed cluster, only to have the drive start failing again just a week later.

Pros: Revising my review.

Cons: One of the drives that were packaged badly died. Fortunately it has been in a mirror and the other one is doing fine. Now I have a problem of backing up the data before attempting to recover from this failure. Removed one additional egg. Will see what the experience with customer support will be.

Overall Review: Gone bad too fast...

Pros: Large amount of data in a single package. Not fast but not slow. Great for my storage and data manipulation servers.

Cons: I am unsure about the quality of these drives. Under heavy usage, SMART reported an increasing number of uncorrectable errors for one of my three drives (all less than a month old). That drive had increasing uncorrectable error counts and randomly went off-line so I filed a RMA. Another disk has a small number of uncorrectable error counts and I am keeping an eye on it. My drives experience heavy usage under ZFS.

Overall Review: Although I believe the drives' quality is a question mark, I have bought two more. I use a fair amount of drives and I am hopeful my experience is an anomaly. I have had trouble with other vendors and models.

Pros: 4TB Good Speeds Reliable So Far Go it for $279.99 Plus Tax At Local Store

Cons: None So Far.