P47781-B21: HPE MR416i-o Gen11 x16 Lanes 8GB Cache OCP SPDM Storage Controller
Also listed as: P47781-001, P47952-001, P47781R-B21 · made by Broadcom
An enterprise OCP 3.0 mezzanine tri-mode storage controller based on Broadcom MegaRAID technology, providing 16 internal lanes and 8GB flash-backed write cache (FBWC). Designed to fit directly into the dedicated rear OCP slot of HPE ProLiant Gen11 servers, it preserves primary PCIe riser slots while managing up to 16 direct SAS, SATA, or NVMe U.3 drives. When purchasing used, inspect the OCP connector contacts and confirm whether the proprietary cache battery backup cable is supplied.
Specifications
| Part number | P47781-B21 |
|---|---|
| Brand | HPE |
| Made by | Broadcom |
| Type | RAID controllers |
| Other numbers | P47781-001, P47952-001, P47781R-B21 |
| Status | current |
| Interface | PCIe 4.0 x8 |
| Form factor | OCP 3.0 mezzanine |
| Cache (GB) | 8 |
| Ports | 16 internal tri-mode lanes (NVMe/SAS/SATA) |
| Generation fit | Gen11 ProLiant servers |
About the P47781-B21
P47781-B21 is HPE's MR416i-o Gen11 Storage Controller, a high-performance tri-mode RAID adapter built in the Open Compute Project (OCP) 3.0 mezzanine form factor. Powered by Broadcom MegaRAID SAS3916 silicon, it integrates 16 internal lanes and 8GB of 72-bit DDR4-2666 Flash-Backed Write Cache (FBWC). It supports hardware RAID 0, 1, 5, 6, 10, 50, and 60 alongside passthrough JBOD modes for up to 16 SAS (12Gb/s), SATA (6Gb/s), or direct-attached NVMe U.3 (16Gb/s) drives. Installing in the dedicated rear OCP mezzanine bay preserves standard PCIe slots for network cards or GPUs.
Compatibility
This controller installs into the internal OCP 3.0 slot in HPE ProLiant Gen11 rack servers including the DL360 Gen11, DL380 Gen11, DL385 Gen11, DL325 Gen11, and DL560 Gen11. Connection to the front drive cages requires server-specific SlimSAS tri-mode cables. Write-cache acceleration requires an HPE Smart Storage energy pack (battery or hybrid capacitor) connected via dedicated onboard header. It does not fit ProLiant Gen10 servers or standard PCIe riser slots. The option SKU is P47781-B21, with spare service number P47952-001.
How to identify a genuine unit
A genuine P47781-B21 unit features an authentic HPE serial label displaying option code P47781-B21, spare number P47952-001, and an integrated OCP 3.0 ejector latch with pull-tab. In iLO 6 under Storage, the controller is identified as the HPE MR416i-o Gen11 Controller, featuring DMTF SPDM security certificate validation and Silicon Root of Trust attestation. Generic or uncertified OCP RAID controllers will fail iLO security authentication and will not link with HPE MR Storage Administrator.
Buying used
When evaluating second-hand MR416i-o controllers, inspect the 4C+ OCP card edge connector pins for damage, scratching, or debris. Verify that the mechanical pull-tab mechanism and retention thumbscrew are in working order. Request a StorCLI diagnostic log from the seller showing that all 8GB of cache memory is functional and verify that the optional energy pack capacitor cable is supplied if write caching is required.
Reference prices (last 14 days, updated 2026-10-27)
New: USD 1,600 to 2,275 (2 sightings, Oct 2026)
All sightings
| Seller | Condition | Price | Note | Seen |
|---|---|---|---|---|
| serversupply.com | new | USD 1,600 | new in box | 2026-10-27 |
| globalonetechnology.com | new | USD 2,275 | sale price | 2026-10-27 |
Prices seen on public listings on the dates shown, before tax and shipping. Not an offer.
Fits these models
- HPE ProLiant DL380 Gen11
- HPE ProLiant DL360 Gen11
- HPE ProLiant DL385 Gen11
- HPE ProLiant DL325 Gen11
- HPE ProLiant DL560 Gen11
Equivalent part numbers
- HPE P47777-B21 HPE MR416i-p Gen11 x16 Lanes 8GB Cache PCI SPDM Storage Controller PCIe HH/HL plug-in form-factor equivalent
FAQ
What is the difference between MR416i-p and MR416i-o?
Both controllers feature identical Broadcom SAS3916 silicon, 16 tri-mode lanes, and 8GB FBWC. The MR416i-p uses a standard PCIe add-in slot, whereas the MR416i-o uses the dedicated rear OCP 3.0 slot, saving a PCIe riser slot.
Does the MR416i-o require an energy pack for write caching?
Yes, enabling write-back caching requires connecting an HPE Smart Storage battery or hybrid capacitor energy pack.
Buying or selling P47781-B21?
New, refurbished or used. Tell us the quantity and condition and we connect you with a vetted reseller in your region, usually within one working day.
Sources
- HPE Compute MR Controllers QuickSpecs, checked 2026-10-27