HP Drive Part Numbers: Spare vs Assembly vs Option
The number printed on an HPE drive label is usually not the number on the purchase order, which is why part-number searches come back empty. How the three numbering schemes relate, what MDL actually means, and how to identify a drive you only have in your hand.
The number on the drive is usually not the number in the quote
This is the single most common reason an HP drive search comes back empty. An HPE drive typically carries more than one identifier, and the one printed on the label is rarely the one written on a purchase order.
You will normally encounter three:
- Spare part number — printed on the drive label itself, often next to "SPS" or
"Spare". This is the number a technician reads off a failed drive.
- Assembly part number — identifies the drive plus its carrier as a serviceable
assembly. Frequently what appears in service documentation.
- Option / SKU part number — the orderable catalogue number HPE quotes and
resellers list. Often ends in a letter suffix such as -B21.
They refer to the same physical drive. They are not interchangeable as search terms, which is why searching the label number on a reseller site can return nothing while the drive is plainly in stock under a different number.
What to do about it
Search every number you have, not just the one you can see. If the label number returns nothing, the option number usually will, and vice versa. Our search matches on all part numbers we hold for a product.
When you only have a dead drive, read the label and note the capacity, RPM and interface as well as the part number. Those three attributes narrow the field fast even if no number matches — a 300 GB 10K SAS 2.5-inch drive is a small set.
When you have an HPE quote, the option number is the safest thing to search.
Midline (MDL) drives — a naming convention worth knowing
HPE labels its high-capacity, lower-RPM drives Midline or MDL. These are the 7,200 RPM bulk-capacity drives, as opposed to the 10K and 15K Enterprise (ENT) line.
If you have seen "MDL" on a spec sheet and assumed it was a model family, it is not — it is a duty class. Midline drives are built for capacity and sequential throughput (backup targets, archives, media), not for the random I/O of a database. Buying MDL where the workload needs ENT is a common and expensive mismatch.
We hold 868 sellable HP midline drives and 5,374 at 7,200 RPM overall.
Matching the drive to the server, not just the bay
A drive that is physically correct can still be rejected. Three things to confirm before ordering:
The carrier generation. HPE changed carrier design across ProLiant generations; a drive in the wrong carrier will not seat or will not be recognised. This is covered properly in the drive carrier guide.
Form factor. SFF (2.5-inch) and LFF (3.5-inch) are not interchangeable without an adapter. We hold 7,500 sellable SFF and 10,412 LFF HP drives.
Interface generation. SAS is backward compatible in a way SATA is not — a SATA drive will not work in a SAS-only backplane, while a 6G SAS drive will negotiate down in a 12G backplane. If you are unsure, the SAS hard drive guide covers the rules.
What we actually stock, by the axes buyers filter on
| Segment | Sellable HP/HPE drives |
|---|---|
| 3.5-inch (LFF) | 10,412 |
| 2.5-inch (SFF) | 7,500 |
| SATA | 6,702 |
| Hot-plug | 6,059 |
| 7,200 RPM | 5,374 |
| SCSI (legacy) | 4,647 |
| SAS | 4,255 |
| 10,000 RPM | 4,021 |
| Solid state | 3,744 |
| 15,000 RPM | 2,509 |
| Fibre Channel | 892 |
| Midline (MDL) | 868 |
Deepest capacities are the ones enterprise fleets actually run: 300 GB (1,005), 146 GB (917), 500 GB (740), 1 TB (650), 600 GB (506).
The short version
- The number on the label and the number in the quote are usually different. Search both.
- MDL is a duty class, not a model line — capacity work, not database work.
- Confirm carrier generation and form factor before interface speed.
- If you only have a dead drive, capacity + RPM + interface narrows it fast enough.
HP Drive Guides
Part of a set covering HP and HPE drives end to end:
- HP enterprise SAS hard drives — speed, interface, form factor
- HP enterprise SSDs — endurance tiers and interfaces
- HP drive part numbers — you are here
- HP ProLiant drive carriers — SC vs BC, SFF vs LFF
- HP ProLiant RAID levels — which level for which workload
- HP storage solutions — how the stack fits together
Where to Buy These Parts
Pro Disk Network holds 20,641 sellable HP and HPE drives, from $47.37. Sourcing by the axis you are actually choosing on:
- By interface - HP ProLiant SAS drives, HP SATA hard drives, HP legacy SCSI drives, Fibre Channel drives
- Solid state - HP SSD, enterprise SSD, NVMe server SSD
- Everything HP storage - HP server storage, enterprise hard drives
- Fitting the drive - HP drive caddies and trays, server drive caddies, drive expansion enclosures
- Controllers - HP Smart Array controllers, enterprise RAID controllers
- Systems and spares - refurbished HPE ProLiant, HP ProLiant parts, HP tape drives
_Pro Disk Network ships from the United States. Stock is refurbished and tested by default; new units are available on request. Contact us for a quote on quantities._