Seagate · Data-centre drive · ST12000NM000J
Seagate Exos X18 12TB
Seagate builds this one for data-centre racks; in a home NAS it's simply a big 7,200 rpm SATA drive with five years' cover.
- Capacity
- 12 TB
- Recording
- CMR
- Speed
- 7,200 rpm
- Warranty
- 5 years
- Workload
- 550 TB/yr
- Failure rate
- AFR 1.10% average
Good for
- Busy arrays (550 TB a year)
- Big media libraries
- 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 Exos X18 12 TB is for
Pick it for raw capacity in a box that lives out of earshot, because 7,200 rpm enterprise drives are built to run flat out all day, every day. Seagate backs it for five years, which is a long time in drive terms. CMR, thankfully. SMR and parity rebuilds don't get on.
Watch out for
It's a 7,200 rpm drive and you'll hear it working.
On Backblaze's numbers it's neither better nor worse than the median, at 1.10% AFR with an interval that straddles 1.38%. Seagate's datasheet puts it at 28 dB idle and 32 dB seeking. Power draw is 4.4 W idle on Seagate's figures, or 39 kWh a year if it spends the whole year idling. A 4-bay box full of these gives 36 TB after one drive's worth of parity.
Specifications
Each value links to the Seagate page or datasheet it came from.
Sources: seagate.com
Failure rate
22 failures in 2,002 drive-years, across the 1,079 that Backblaze runs as ST12000NM000J, works out at 1.10% a year. Its 95% interval is 0.69% to 1.66%, a range wide enough to include the 1.38% median.
Median lifetime AFR across Backblaze drive models: 1.38%
Source: Backblaze Drive Stats, lifetime to Q2 2026. Bear in mind that's data-centre use, which is a lot harder on a drive than a home NAS will ever be.