WD Ultrastar HC550 16TB

What it is

Western Digital's 16TB enterprise helium drive, the direct competitor to the Seagate Exos line. CMR recording, 24/7 rated, 2.5 million hour MTBF. Performance is close enough to the Exos that price and SMART health should decide which you buy rather than brand preference.

What to check before you buy

• Same SATA versus SAS question. Confirm the interface before buying.
• Request SMART data, specifically power-on hours and reallocated sectors.
• 512e versus 4Kn formatting matters for some controllers. Ask which it is.
• Mixing drive models across a ZFS vdev is fine, but keep capacities identical.

What a fair price looks like

Across 1 listings tracked in the last three days, the median total cost in USD including shipping is $350, and the lowest is $350. RackSniper flags a listing once it falls at or below 70 percent of the trailing 30 day median, which for this product means roughly $245 or less. Condition and configuration vary widely on used enterprise hardware, so treat the median as a reference point rather than a target.