WD80EFPX specs explained: what WD’s 8TB Red Plus numbers mean in a NAS

What the numbers mean

Capacity: 8TB on the label, about 7.28 TiB in your NAS

The datasheet states a formatted capacity of 8TB, and its footnote counts 1TB as one trillion bytes. An operating system or NAS dashboard that counts in binary units, where 1 TiB is 1,099,511,627,776 bytes, reports the same drive as about 7.28 TiB (8,000,000,000,000 ÷ 1,099,511,627,776). Nothing is missing: same bytes, counted two ways.

Usable space in a RAID array

WD states the drive for NAS systems with up to 8 bays, so the practical question is what a set of them gives you. RAID 1 and RAID 5 give up one drive’s worth of space to redundancy, RAID 6 two drives’ worth. With 8TB drives the arithmetic is:

Speed: about 10.3 hours for one full pass

The datasheet states 5640 RPM and an internal transfer rate of up to 215MB/s, counting 1MB/s as one million bytes per second. At that rate the drive moves about 774GB an hour (215MB × 3,600 seconds), and one pass over all 8TB takes at least 10.3 hours (8,000,000MB ÷ 215MB/s ≈ 37,200 seconds). That is the floor for any job that touches every sector once: copying a full drive, a full data scrub, or writing a replacement drive during a RAID rebuild. Since 215MB/s is an “up to” maximum, a real full pass takes longer.

Interface: SATA 6 Gb/s has room to spare

The datasheet states a 3.5-inch drive on SATA 6 Gb/s. In bits, its 215MB/s maximum is 1.72 Gb/s (215 × 8 = 1,720 Mb/s), under a third of the 6 Gb/s link: the drive, not the link, sets the speed. WD lists the drive technology as Air.

Recording: CMR, from WD’s own table

The datasheet lists the recording technology as CMR (conventional magnetic recording), which settles the “CMR or SMR” question for this model from WD’s own specifications table.

Cache: 256MB, and why the model number matters

The datasheet states 256MB of cache. WD’s Red Plus table has two models of this capacity: the WD80EFPX and the WD80EFZZ, each with its own column and with different figures for cache, transfer rate, power, noise and weight. The WD80EFBX doesn’t appear in WD’s March 2025 brief, nor on WD’s US and UK product pages as of 2026-10-28, so WD gives no figures for it to compare. If a product page says “WD Red Plus 8TB” without a model number, this page may not describe the drive it sells: look for WD80EFPX.

Workload: 180TB a year is about 493GB a day

The datasheet rates the drive for 180TB a year of workload, and its footnote counts data transferred both to and from the drive, so reads count as well as writes. That is about 493GB a day (180TB ÷ 365), or 22.5 passes over the full 8TB a year (180 ÷ 8). Scheduled maintenance uses this budget too: a monthly full scrub of a full drive reads 96TB a year (12 × 8TB), more than half the rating before any of your own files move. The rating is per drive.

MTBF: 1,000,000 hours at half the rated workload

The datasheet states an MTBF of 1,000,000 hours, under a 90TB/year workload and a 40°C drive temperature. The test load is half the 180TB/year rating (90 ÷ 180), so the figure describes a drive at half its rated load, not a busier or hotter one. MTBF describes a large group of drives, not the lifespan of yours. As a rough conversion, a year of 24/7 operation is 8,760 hours, and 8,760 ÷ 1,000,000 is 0.876%: an annualized failure rate a little under 1 in 100, under WD’s test conditions.

Read errors: fewer than 1 in 10¹⁴ bits

The datasheet states fewer than 1 non-recoverable error per 10¹⁴ bits read. That many bits is 12.5TB (10¹⁴ ÷ 8 bits per byte = 12.5 trillion bytes), so one full read of this 8TB drive covers 64% of that span (8 ÷ 12.5). The figure is a ceiling, not a forecast, but it matters for single-parity arrays: rebuilding a four-drive RAID 5 of these drives reads the three survivors end to end, 24TB, almost twice 12.5TB. One more reason to keep a backup outside the array.

Load/unload cycles: about 548 head parks a day

The datasheet rates the drive for 600,000 load/unload cycles, the times the heads park and return to the platters. Spread across the 3-year limited warranty, that is about 548 a day (600,000 ÷ 1,095 days), or about 23 an hour. Aggressive power saving spends this budget: parking once every five minutes, around the clock, uses 288 a day (1,440 minutes ÷ 5).

Power: about 30kWh a year per idle drive

The datasheet lists average power of 5.2 W in read/write, 3.4 W at idle and 0.4 W in standby and sleep. A drive idling around the clock uses about 29.8kWh a year (3.4 W × 8,760 hours = 29,784Wh); spun down, about 3.5kWh (0.4 W × 8,760 hours). In a full 8-bay NAS, the drives alone draw about 41.6 W in read/write (8 × 5.2 W) and 27.2 W at idle (8 × 3.4 W), before the NAS itself: the drive share to count when sizing a UPS.

Noise: 24 dBA idle, 28 dBA seeking

The datasheet lists acoustics of 24 dBA at idle and 28 dBA in seek (average). The drive is 4 dBA louder when busy finding data than when only spinning. WD doesn’t state how or from what distance it measured, so these figures compare drives within WD’s own brief, not against other brands’ numbers.

Temperature: 0 to 65°C operating

The datasheet lists an operating range of 0 to 65°C, while the MTBF figure assumes 40°C, 25°C below the top of that range (65 − 40). A NAS that keeps its drives at or below 40°C stays within the temperature WD quotes for its MTBF figure, not just the range it allows; WD notes that MTBF is derated above its test conditions.

Up to 8 bays: WD’s stated use, not a hardware limit

WD states the drive is “for RAID-optimized NAS systems with up to 8 bays”. That is intended use, not a technical limit WD publishes: in a 12-bay chassis the drive is outside the use WD rates it for. WD also says its NASware technology tunes drive parameters to NAS workloads and its dual-plane balance control improves balance: WD’s descriptions, not measured figures.

Warranty and weight

The datasheet lists a 3-year limited warranty, with terms that vary by region. Each drive weighs 715 g (± 10%), so four of them add about 2.86 kg (4 × 715 g) to a NAS.