Seagate ST1000NX0313 1TB SAS 2.5in Nearline HDD: Specs and Chassis Fit
A 2.5-inch nearline drive is an unusual combination. Small form factor normally means performance — 10K and 15K spindles packed densely for IOPS. Nearline normally means 3.5-inch, where capacity per drive is cheapest.
The Seagate ST1000NX0313 is 1TB of 7200RPM nearline storage on a SAS 12Gb/s interface in a 2.5-inch package, and it exists to solve a specific problem: capacity in a chassis that has no room for large-format drives.
Why small-format capacity storage exists
Server chassis are built around one form factor or the other. A 2U server with twenty-four small-form-factor bays cannot accept a 3.5-inch drive at all — the bays are physically the wrong size and the backplane connectors are positioned differently.
That creates a real constraint. If your chassis is SFF and you need bulk capacity for a backup volume, an archive tier or a large file share, you cannot simply order 3.5-inch nearline drives. You need capacity drives in the form factor the chassis takes.
Three situations where this comes up constantly:
Mixed-tier servers. A host running 15K SFF drives for its transactional volumes and needing a capacity volume on the same chassis, without adding a separate enclosure.
Blade and dense compute. Systems where 3.5-inch simply is not an option at any point in the design.
Rack density constraints. Where adding a 3.5-inch enclosure means adding rack units, and rack units are the scarce resource.
In all three, an SFF nearline drive is the only shape that fits.
ST1000NX0313 specifications
| Part Number | ST1000NX0313 |
| Manufacturer | Seagate |
| Product Family | Exos |
| Capacity | 1TB |
| Interface | SAS 12Gb/s |
| Rotational Speed | 7200 RPM |
| Form Factor | 2.5 inch SFF |
| Drive Class | Nearline |
| Condition | Refurbished, function-tested |
| Warranty | 30-day TechSellerUSA warranty |
The trade-off you are accepting
Being honest about this matters, because the wrong expectation causes disappointment that gets blamed on the drive.
Capacity per drive is lower. A 2.5-inch platter is physically smaller, so SFF nearline capacities top out well below what 3.5-inch drives reach. If your chassis takes large-format drives, they will always give you more terabytes per bay for less money.
Cost per terabyte is higher. You are paying a premium for the form factor, not for performance. That premium is worth it when the alternative is buying and racking an additional enclosure, and it is not worth it when you simply have not checked what your chassis supports.
It is still 7200 RPM. The small form factor does not make it fast. This is capacity storage in a compact package, not a performance drive. For transactional workloads in the same chassis you still want 15K SFF drives.
The correct mental model: this drive is a solution to a physical constraint, not a performance or economic optimisation.
SKU: ST1000NX0313  | Refurbished & function-tested  | 30-day warranty
View Details & Request a Quote →SAS on a capacity drive
This is a SAS drive rather than SATA, which matters more in an SFF chassis than it might elsewhere.
Dense SFF backplanes typically use SAS expanders to connect twenty-four bays to a controller with far fewer ports. SAS drives handle expander topologies natively with dual-port paths; SATA drives work through expanders using a translation layer that adds overhead and gives up path redundancy.
In a chassis that already has SAS drives in other bays, keeping the capacity tier on SAS also keeps the whole backplane consistent, which avoids a class of odd behaviour that appears when SAS and SATA are mixed behind the same expander.
The 12Gb/s interface runs at 6Gb/s in older backplanes with no issue, so a mixed-generation fleet can standardise on one part number.
Where it fits, concretely
Backup and archive volumes on an SFF server, log and audit retention alongside a transactional workload, video and media storage in a dense chassis, secondary tiers behind faster storage, and any bulk requirement where adding a 3.5-inch enclosure is not practical.
It is the wrong choice if your chassis takes large-format drives, where 3.5-inch nearline drives give more capacity per bay for less. Check the chassis before ordering rather than after — our compatibility guide covers form factor and carrier requirements by platform.
Ordering
We supply the ST1000NX0313 refurbished and function-tested with a 30-day warranty, single spares or in volume for bay population. Browse the full Seagate range or our complete enterprise hard drives catalogue.
Common questions
Why buy a 2.5-inch nearline drive instead of 3.5-inch?
Because the chassis takes small-form-factor bays and physically cannot accept 3.5-inch drives. If your chassis does take large-format drives, they give more capacity per bay for less money and are the better choice.
Is a small-form-factor drive faster?
Not inherently. Form factor and spindle speed are separate specifications. This is a 7200 RPM capacity drive in a compact package. For transactional workloads in the same chassis you still need 10K or 15K SFF drives.
Why SAS rather than SATA on a capacity drive?
Dense SFF backplanes use SAS expanders to connect many bays to fewer controller ports. SAS drives handle expander topologies natively with dual-port paths; SATA works through a translation layer that adds overhead and gives up path redundancy.
Will a 12Gb/s drive work in an older 6Gb/s backplane?
Yes, at the lower link speed. That backward compatibility means a mixed-generation fleet can standardise on a single part number rather than stocking two.
Tell us your chassis model and bay count and we will confirm form factor and carrier before quoting.
