Transfer Rate Range

This chart shows you the range of platter-to-buffer transfer rates from the innermost track to the outermost track. In other words, it shows you the range of disk transfer rates of the hard drives (from minimum and maximum).

The new WD20EARX was surprisingly slower than the older 2 TB Western Digital Caviar Green (WD20EARS). Although Western Digital claimed that both drives ran at the same spindle speed, our test results showed that the new WD20EARS is actually spinning slower by about 4.6%.

The reduced spindle speed puts the new 2 TB Caviar Green just a tad behind the latest 3 TB Western Digital Caviar Green 6 Gbps (WD30EZRX) hard disk drive. Both these drives have the same throughput at the outer tracks, but the WD30EZRX won at the end, due to its better performance at the slower inner tracks.

Platter Transfer Rate Profile

Here, we compared the WD20EARX's platter profile with its SATA 3.0 Gb/s brother, the Western Digital WD20EARS.

The maximum platter transfer rate appeared to be about 128 MB/s which progressively dropped across the platter to about 50 MB/s at the last track. This drive has about 21 density zones. The platter quality seems to be very good in this sample, with only one large dip that would suggest the use of replacement sectors.

As you can see, the new WD20EARX is slightly slower than the previous generation WD20EARS. Therefore, even though the WD20EARX supports SATA 6.0 Gb/s while the WD20EARS can only support SATA 3.0 Gbps, we expect the older WD20EARS to deliver better performance than the new WD20EARX.

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