874566-B21 is the HPE option part number for ML350 Gen10 4LFF Hot Plug Drive Backplane Cage Kit. The kit adds a four-bay hot-plug drive cage and backplane assembly for 3.5-inch large form factor drives in the ML350 Gen10 tower server. Each of the four bays supports hot-swap operation, so drives can be added or replaced without taking the chassis apart. It is a storage capacity option only; no processor is included, and drives are ordered separately. Use it when planning LFF storage capacity into a new ML350 Gen10 build or expanding an existing configuration that has open drive cage positions.
HPE Option Part #: 874566-B21
PRODUCT SPECIFICATIONS FOR 874566-B21:
- Device Type: Storage drive cage
- Hard Drive Form Factor Compatibility: 3.5"
- Processor: No CPU
- Bays: 4 x hot-swap - 3.5" LFF
COMPATIBLE WITH:
PROLIANT ML SERIES
** This list may not be complete. Contact us via Live Chat if you have any questions about compatibility.
FREQUENTLY ASKED QUESTIONS ABOUT 874566-B21
What does the 874566-B21 kit include?
The kit is a storage drive cage assembly providing four hot-swap 3.5-inch LFF drive bays, along with the associated backplane. It is supplied as a cage and backplane option, not as a populated storage unit. Hard drives are not part of the kit and must be selected separately. No processor is included with this option, as it is purely a storage enclosure component.
Which server does this cage kit fit?
The 874566-B21 cage kit is designed for the HPE ML350 Gen10 server. It mounts into the drive cage positions of that chassis and connects to the server's storage subsystem through the included backplane. Because the mechanical and backplane design is specific to the ML350 Gen10, this kit should not be planned into other server generations or model families.
What drive form factor does it support?
This cage supports 3.5-inch large form factor drives only. Each of the four bays is a hot-plug LFF position, so drives can be inserted or removed while the server remains running, subject to the RAID or storage controller configuration in use. If your build requires small form factor drives, this kit is not the correct option.
How many drives can I add with one kit?
One 874566-B21 kit provides four hot-swap 3.5-inch LFF bays. If your ML350 Gen10 chassis has additional open drive cage positions, further capacity is added by installing additional cage kits, up to the limits supported by your chassis configuration and storage controller port count. Confirm available cage positions and controller connectivity before deciding how many kits to configure.
Does this kit include a controller or processor?
No. The 874566-B21 is a drive cage and backplane assembly. It contains no CPU and does not ship with a storage controller or drives. The backplane connects the four LFF bays to a storage controller that is configured elsewhere in the server. Plan controller ports, cabling and drive selection alongside this option when specifying an ML350 Gen10 build.
HPE PARTSURFER INFO FOR 874566-B21
| Spare PN | Description | |
|---|---|---|
 | 827363-001 | Blank Large Form Factor (LFF) reduced depth |
| 809955-001 | Miscellaneous blank kit for Apollo 4200 - Includes air blocker for PCIe expansion slots 5-7, air blocker for front 2-drive cage backplane, chassis retention bracket, fan blank, LFF and SFF drive blank, cable management holder, and FlexibleLOM blank |
| 878930-001 | Hot Plug Hard drive backplane supports 4-Large Form Factor (LFF), 12 Gb/s transfer rate SAS |
Last Updated: 2026-08-09
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This product is warrantied against hardware failure for a period of 1 Year from the date of purchase. Before making a purchase, please take a moment to review our return policy below.
Returns
It is the customer's responsibility to verify compatibility with their machine(s) before placing an order. If an item is ordered by mistake, it can be returned for refund, minus a 25% restocking fee, within 5 business days of receipt. The cost of freight is not refundable.
Please be aware that factory-sealed equipment can only be returned if it remains unopened.
Defective Products
If you have received a defective part and your machine is still within the HPE warranty period, please initiate a warranty exchange by visiting the HPE Enterprise Support Center. Be sure to have the serial numbers of the defective drive and your server/storage array handy.
In case your hardware becomes defective during the Global One warranty period, but the HPE warranty has expired, you can return the product to us for a working replacement. You are responsible for the shipment of returned merchandise. However, we will cover the expense of Ground /Economy shipment for the replacement item(s).
Requesting an RMA
To initiate a return or warranty claim, please complete and submit the RMA Request Form.
