Deskstar 7K4000: 4 TB in 3.5 Inches

New Update

Deskstar 7K4000 is aimed squarely at providing desktop PCs with enormous storage capacity, as the name suggests. Just to give you an idea of its size, the HDD can store up to 6,000 movies (considering an average movie size of 700 MB). If you play all of them in sequence, then besides getting sick, you would also end up spending 500 days of your life! The last time we tested 4 TB  storage capacity in our labs was with an entry level, 4 Bay NAS box. The mere ability of squeezing four 1 TB hard drives into one big drive is what made us interested in diving deep into this drive. Two questions immediately come to my mind about this drive. One, how has such huge capacity been made available in the same 3.5 inch form factor? Two, what sort of performance does it offer? Read more to find the answer.


Advanced Format Technology

In a typical drive, data is stored in 512-byte sector sizes. Each sector, besides storing users' data, also stores overhead data including the error correction code (ECC) and drive format information (Gap, Sync, Data Address Mark). The Advanced Format drives use longer sectors that contain 4096 (4K) bytes, which is the equivalent of putting eight historical (512-byte) sectors into one new 4K sector. This approach provides two benefits -first, by optimizing the overhead associated with each smaller sector, the drive uses lesser space to store the same amount of information resulting in a format efficiency improvement. The second benefit is that a larger and more powerful error correction code (ECC) can be utilized, providing better integrity of user data. There are many existing hardware and software components that are designed around 512-byte sector

(or block) sizes and expect data to be sent and received in 512-byte segments. In order to maintain compatibility with these legacy applications, 512-byte  emulation is provided on the drive which transparently maps all 512-byte logical

blocks into the drive's 4K physical sectors. Before you use more than 2.2 TB

drive space Due to traditional 32-bit definitions used for partition size and logical block addresses (LBA), you can't use hard drives that have more than 2.2 TB. So, in order to use 4 TB drives, you have to take a combination of the operating system, BIOS, drive partition tables, and HDD measures.

In order to store data on a hard drive, it must first be partitioned. A partition table tells the computer how data on the drive is laid out, including the size of the drive. Historically, PCs have partitioned the hard drive using a Master Boot Record (MBR). Unfortunately, the MBR is limited to partitions smaller than 2.2TB. To address this problem, a new partition table scheme known as GUID Partition Table (GPT) needs to be used. In order to use a GPT based drive as a bootable drive, you need to use UEFI BIOS standard. Besides, you also have to update storage drives to utilize more than 2.2 TB capacity. Refer to the table to check out which OS supports more than 2.2 TB drive.



In order to check performance of this 7200 RPM drive with 64 MB cache we used Windows 7 ultimate 64 bit OS with 4 GB of RAM and AMD A10 3.8 GHz processor. Benchmark used in our test was HD Tune 2.55. We found that the Deskstar 7K4000 was able to give transfer rate of 151 MB/s in average, with access time of an amazing 10.2 ms. This result is better than the Deskstar 7K3000 (, which scored 113.9 MB/s @ 16 ms).

Bottomline: A single drive that can take care of all your data storage worries without any performance degradation. Definitely worth buying!


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