Rackmount Raspberry Pi CM4 cluster system offers modular I/O
Sep 1, 2021 — by Eric Brown 2,181 viewsTechbase’s “ClusBerry Rack” rackmount cluster system can load up to 4x hot-swap RPi CM4 modules, each with GbE, USB 2.0, micro-USB, serial, 5V, and optional PoE, M.2, and wireless. Meanwhile, the dual CM4 “ClusBerry-2M” ships in a few weeks.
In February, Techbase launched a series of ClusBerry clustering systems for the Raspberry Pi Compute Module 4, including desktop and DIN-rail models for up to 8x CM4 modules. Now, the company has unveiled a ClusBerry Rack rackmount model for up to 4x CM4 modules, each with its own set of modular I/Os.


ClusBerry Rack (left) and ClusBerry-2M
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The ClusBerry Rack will ship around Nov. 1 at an undisclosed price. Techbase also says that a dual-CM4 ClusBerry-2M system announced in May will ship in 2-4 weeks (see farther below).
Both products ship with pre-installed modules, and the ship dates are dependent on RPi CM4 supply. If you order them on your own, it will likely take longer. The wait time is up to four months on Digi-Key.
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![]() ModBerry 500 CM4 |
Unlike most clustering systems, the ClusBerry devices offer a variety of I/O ports for each module. The Rack uses much of the same modular I/O scheme available with Techbase’s CM4-based automation controllers, such as the ModBerry 500 CM4.
The ClusBerry Rack provides the same software cluster management tools as the earlier ClusBerry systems, including support for Docker and K3s lightweight Kubernetes. The announcement mentions supported Kubernetes functions including load balancing, storage mounting, automatic deployment and rollback, resource management via containers, self-healing reboots, and with the help of the TPM option, management of passwords, tokens, and keys.
Each module board can perform various applications ranging from I/O gateway, wireless modem, GbE router, NAS file server, or even an edge AI system when configured with Google Coral Edge TPU modules. Other features include the ability to “boot modules from one to another, upgrade firmware crosswise, and provide safe operation of each module,” says Techbase.


ClusBerry Rack (left) and detail view of standard CM4 mainboard
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The rackmount form-factor ClusBerry Rack differs from the other ClusBerry systems in that it lets you upgrade or change cluster modules on the fly. It also has different standard I/O features than the other ClusBerry models, giving you GbE, USB 2.0, and micro-USB “service” ports on each 100 x 70mm module mainboard. Each board also provides a 6-pin RS-232/485 interface, a 5V power supply, and a user-controlled button and LEDs.
ClusBerry Rack options include a second GbE port with 30W Power-over-Ethernet plus an HDMI port and TPM 2.0 security. Other options include an M.2 slot for an NVMe SSD and 2x mini-PCIe slots for options include 4G/LTE, 5G, NarrowBand-IoT, LoRa, ZigBee, Z-Wave, Sigfox, Wireless M-Bus, and either a standard WiFi/Bluetooth module or “Wi-Fi Hi-Power” modem. It appears you can also purchase the CM4 with the WiFi/BT option.
ClusBerry-2M
The soon-to-ship ClusBerry-2M looks like two ModBerry 500 CM4 automation controllers joined at the hip. It provides essentially the same functionality along with clustering support. Designed primarily for IoT prototyping rather than more typical clustering projects, the dual-CM4 ClusBerry-2M supports the same software as other ClusBerry systems.

ClusBerry-2M
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The standard ClusBerry-2M is equipped with dual M.2 slots for NVMe SSDs and offers up to 4x mini-PCIe slots for wireless expansion. Other expansion options appear to be similar.
Further information
No pricing information was provided for the ClusBerry Rack and ClusBerry-2M. The ClusBerry Rack is scheduled to ship around Nov. 1 and the ClusBerry-2M in 2-4 weeks. More information on the ClusBerry Rack should eventually be found on the Techbase website or shopping site. More on the ClusBerry-2M may be found on this shopping page.
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