HPE lists the same physical component under more than one number. This guide explains option part numbers, spare part numbers, the suffixes that matter and the lookup tools that settle a fitment question quickly.
Nearly every fitment dispute we see on HPE kit comes down to the same thing: two numbers for one component. Here is how to read them.
The two numbers on every HPE option
- Option part number: the number HPE sells the item under as an orderable kit. It normally ends in a suffix such as -B21. It includes the accessories needed to fit the part, for example the drive carrier with a drive or the cable kit with a controller.
- Spare part number: the number printed on the component label, used for warranty replacement. It usually ends in -001 and is the bare part with no kit content.
- Assembly or exchange numbers also appear on labels and refer to the sub-assembly HPE ships to engineers.
- The same drive can therefore appear under three numbers. Search on all of them before deciding two listings are different products.
If a price looks unusually low for a drive or controller, check which number is being quoted. A spare part number frequently means no caddy, no cables and no bracket.
Suffixes and what they signal
- -B21 is the common option kit suffix; other -Bxx suffixes exist across the catalogue.
- -001 typically marks a spare or replacement part number.
- A #xxx suffix such as #0D1 or a country code marks a factory-integrated or localised variant, common on CTO servers.
- Trailing letters on server model part numbers can carry a regional or TAA designation. Two servers with the same base number and different suffixes are not always interchangeable for support purposes.
Component families where the number matters most
| Family | What to check | Why it bites |
|---|---|---|
| Drives | Generation of caddy, SAS vs SATA vs NVMe, capacity point | Gen8 to Gen10 and Gen11 carriers differ; a bare drive with the wrong tray will not seat |
| Memory | Rank, RDIMM vs LRDIMM, speed, DDR4 vs DDR5, Smart Memory | Mixing ranks or speeds forces the whole bank down to the slowest DIMM |
| Storage controllers | Gen11 MR and SR series, cache size, -o (OCP) vs -p (PCIe) form factor | MR416i-o and MR416i-p are the same class of controller in physically different slots |
| Boot devices | NS204i-u versus NS204i-u V2 and platform support | V2 is compatible with a different platform list, per the HPE OS Boot Device QuickSpecs |
| Risers and cables | Chassis, slot count and CPU population | Second-socket risers are inactive on single-socket configurations |
| Power supplies | Watt rating, Flex Slot vs older form factors, efficiency class | Mixing ratings in one chassis is unsupported |
Lookup workflow that settles it
- Start with the server QuickSpecs. Its option tables list the exact numbers supported on that platform, which is the definitive compatibility answer.
- Use HPE PartSurfer with the serial number to see what is actually fitted in a specific unit, or with a part number to find its equivalents.
- Where a component is end of sale, check the QuickSpecs for the replacement part number rather than assuming an equivalent capacity fits.
- Photograph the label. Both numbers are usually printed on it, and that single photo answers most fitment questions immediately.
The ETON view
This is where secondary-market buying goes wrong, and it is avoidable. Sourcing on a spare part number and receiving a bare drive with no carrier is a two-week delay on a build for the sake of a caddy, and mixed DIMM ranks quietly cost you memory bandwidth that nobody measures until an application is slow. Our approach is to quote on the option part number wherever we can, state what is in the box, and confirm the carrier and cable content before anything ships.
If you have a part number and are not sure what it fits, send it to us with the server model. We will tell you what it is, whether it fits, what we hold, and what the equivalent is if the original is end of sale.
Related infrastructure
Category: Servers · Vendor: HPE · Technology: HPE option and spare part numbering, PartSurfer, QuickSpecs · Last verified: 09 Sep 2026 · ~3 min read
Sourcing this kind of infrastructure? Talk to ETON about availability, lead time and pricing.
