WD Red Pro 20TB HDD Review

1. Introduction2. WD Red Pro 20TB3. Testing Methodology4. CrystalDiskMark5. ATTO Disk Benchmark6. 4K Random Performance7. Throughput8. Workload Scenarios9. Real Life File Testing10. Closing Thoughts11. View All Pages

WD has recently added 20TB capacity drives to a number of their HDD product lines. One of these is the NAS focused Red Pro range which officially supports NAS devices using up to 24 bays in size. The drive features a number of WD's current HDD technologies as well as more NAS-focused Red Pro features and uses WD's latest nine disk platform. The 20TB Red Pro has a spindle speed of 7,200rpm and comes with 512MB of cache.

Each 2.2TB disc has an areal density of 1,160 Gbits/in² and to overcome the potential track problems caused by such dense discs, the drive uses two WD technologies; triple-stage actuator (TSA) and Energy-Assisted Perpendicular Magnetic Recording (ePMR). TSA uses three pivot points in the actuator arm to more accurately position the head over the data track. ePMR is a technology to overcome something called jitters. Jitters occur when the write current at the recording head is flipped from one direction to another, ePMR applies a constant electrical current to the main pole of the write head throughout the write process, producing a more consistent, preferred signal path that helps to reduce jitter. Reducing jitters allows for the reduction of space between bits written which in turn allows for greater areal densities and larger capacities.

As with the Ultrastar DC H560, we reviewed recently, the 20TB Red Pro uses WD's OptiNAND technology. OptiNAND technology is a flash-enhanced drive technology developed by WD that integrates an iNAND UFS embedded flash drive (EFD), using 3D NAND, that sits on the hard drive PCB.  The NAND isn't used to store user data as per the hybrid drives of the past but instead is used to store the self-generated drive metadata instead of holding it on the disks themselves, freeing up more usable space.

Having said that, user data isn't stored in the NAND, except for one situation where it is – sudden power loss. If power is lost during the write process the SoC uses the rotational power of the still spinning disks to power up internal capacitors until any cached data transfers to the non-volatile NAND.

WD quote a sustained transfer rate of 268MB/s for the 20TB Red Pro which is very slightly slower than the 18TB version. When tested with the ATTO benchmark we could confirm that figure with test results of 260MB/s and 261MB/s for Sequential read and writes respectively. The drive also performed very well in our workload scenarios, producing the best performance figures we’ve seen to date for an HDD in the File Server test.

The official workload rate for the 20TB Red Pro is 300TB/year, which is the figure for the whole Red Pro range from the 2TB model upwards. WD back the Red Pro with a 5-year warranty.

We found the 20TB version of the Red Pro for £612.99 (inc VAT) on WD's online shop HERE.

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Pros

• Overall performance.
• Drive technologies.
• NAS focussed features.

Cons

• All that technology doesn't come cheap.
  

KitGuru says: WD's 20TB Red Pro drive combines some of WD's latest thinking on CMR hard drive technology, alongside the long-standing NAS feature set of the Red Pro product line. But, and it's a pretty big but, it does come with a hefty price tag.

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