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Western Digital · NAS Pro drive · WD4006FFBX

WD Red Pro 4TB

The pro end of WD's NAS range, with no limit on bay count and a 550 TB a year workload rating.

Capacity
4 TB
Recording
CMR
Speed
7,200 rpm
Warranty
5 years
Workload
550 TB/yr
Rated for
Any bay count
Failure rate
No failure data

Good for

  • Any size of NAS
  • Busy arrays (550 TB a year)
  • RAID, SHR and ZFS rebuilds
  • 5 years' warranty

Not for

  • A desk or bedroom (7,200 rpm is the louder class)

Updated 27 Oct 2026 · Method 2.0

Who the WD Red Pro 4 TB is for

This is the one to look at once you're past eight bays or the array's busy all day, because WD rates it for 550 TB a year and doesn't care how big the box is. You also get five years' warranty, two more than the cheapest NAS lines. It's CMR, which is what you want anywhere near a RAID or ZFS rebuild.

Watch out for

It's a 7,200 rpm drive and you'll hear it working.

There's no Backblaze data worth quoting here. Four of them in SHR or RAID 5 give 12 TB usable, or 10.9 TB once Windows has done its binary maths on it.

Specifications

Each value links to the Western Digital page or datasheet it came from.

WD Red Pro 4TB specifications
Drive type NAS source for Drive type (documents.westerndigital.com, opens in new tab)
Capacity 4 TB source for Capacity (westerndigital.com, opens in new tab)
Spindle speed 7,200 rpm source for Spindle speed (westerndigital.com, opens in new tab)
Recording technology CMR source for Recording technology (westerndigital.com, opens in new tab)
Cache 256 MB source for Cache (westerndigital.com, opens in new tab)
Interface SATA 6Gb/s source for Interface (documents.westerndigital.com, opens in new tab)
Form factor 3.5in source for Form factor (westerndigital.com, opens in new tab)
Max sustained transfer 217 MB/s source for Max sustained transfer (westerndigital.com, opens in new tab)
Workload rating 550 TB/yr source for Workload rating (westerndigital.com, opens in new tab)
Rated for any number of NAS bays Yes source for Rated for any number of NAS bays (westerndigital.com, opens in new tab)
Warranty 5 years source for Warranty (westerndigital.com, opens in new tab)

Sources: westerndigital.com, documents.westerndigital.com