The 8TB WD Gold Datacenter Drive (WD8002FRYZ) Review

Page 2 : The 8TB WD Gold Datacenter Drive, HelioSeal & Media Caching Technologies

The 8TB WD Gold Datacenter Drive

Despite featuring a hermetically-sealed chassis, the 8TB WD Gold (WD8002FRYZ) datacenter drive looks deceptively like any other 3.5″ desktop hard disk drive. In fact, it has the same label on the top plate, with an uncovered PCB on the underside.

The label has a lot of important information, like the hard drive model, storage capacity as well as its date and place of manufacture. This particular drive was manufactured in Thailand on the 26th of March, 2016. You can also see that the drive uses the Advanced Format Technology to achieve its high storage density.


HelioSeal Technology

The 8TB WD Gold datacenter drive is one of the few hard disk drives in the market to feature the revolutionary HGST HelioSeal technology. It is hermetically sealed at the factory, and filled with helium. The hole, which normally serves as the breather hole in a normal “air-filled” hard disk drive, is likely the port through which the air is extracted and replaced with helium.

Because helium is only 1/7th the density of “regular air”, it allows for less friction conferring the following benefits :

  • The lower friction reduces the amount of power required to spin the platters, reducing both energy costs and thermal output.
  • Internal turbulence is greatly reduced, which makes tracking more precise and reliable. This indirectly allows for greater areal density.
  • The lower power requirement and internal turbulence allow more platters and heads to be added in the same volume of space.
  • The completely sealed environment eliminates reliability issues that can occur if breather filters get clogged up with dirt.

The only things stopping helium-filled drives from becoming mainstream are the relatively high cost of helium, and the difficulty in sealing the drive.


Media Caching Technology

This feature was mentioned only perfunctorily in the Western Digital press release, which led many writers to assume that they added a NAND flash cache, like the ones used in SSHDs (examples : 4TB WD Blue SSHD, 1TB WD Blue SSHD). Unfortunately, that’s not true.

The media caching technology used in the WD Gold datacenter drives are also a HGST technology, like HelioSeal. It doesn’t use any additional components, just the existing SDRAM cache and the hard disk drive platters. This is how it works :

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  • Small media cache areas are created in regular intervals across the platters. These are only visible to the drive controller, and are hidden to the computer and operating system.
  • Data written to the SDRAM cache are combined and regularly written down to the nearest media cache areas at a higher internal queue depth.
  • These dispersed media cache areas boost write performance by greatly reducing head movements as data is written to the drive.
  • The write data is simultaneously de-staged, which eliminates burst activity and their impact on reads from the platters.
  • In the event of a sudden power-off event, the media cache areas is used to quickly restore the SDRAM cache.

Generally, the media caching technology increases random write performance with a slight boost in read performance.

Next Page > SATA 6 Gb/s, What’s Under The PCB?


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