This document describes the different PCB(Printed Circuit Board). They should all be hot-pluggable :
* Motherboard/backplane
* PSU(Power supply Unit)s PCB 
* UPS(Uninterruptible Power Supply) PCB
* NIC(Network Interface Controller) PCBs
* Microcontroller/Microprocessor PCB
* Hakeva Core PCBs
* RAM(Random Access Memory) PCBs

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!HardwareArchitectureOverview.png!

h1. Backplane/Motherbord

The size has respect an ATX standard to fit in standard racks. Micro-ATX

https://web.archive.org/web/20120725150314/http://www.formfactors.org/developer/specs/atx2_2.pdf

h2. Connectors

* ATX Power
* JTAG
* I2C
* UART
* FTDI/USB to UART
* Connection BUS (2 microcontrolers, 1 UPS, 2 PSU, 5 RAM or FPGA)
* Front panel (Power, Alert and Reset buttons, Power, Alert, Heartbeat1, Heartbeat2, LEDs)
* 2x 3pins PWM Global FAN connectors

h2. Connection bus

 * Power : -12V, -5V, GND, +3.3V, +5V, +12V

 * JTAG : TDI(Test Data In), TDO(Test Data Out), TCK(Test Clock), TMS(Test Mode Select), TRST(Test Reset)

 * I²C : SDA(Serial Data), SCL(Serial Clock)

 * RAM bus : Addr lines, Data lines, BankSelect?, WE, OE, CLK?

It has connectors to support module hotplug :
* Memory modules with standard DDR2 (DDR3/4/5 if possible)
* Storage modules with up-to 4 x Standard 2.5' HDD/SSD for persistence and RAID 0, 1, 10, 5 support
* PSU(Power Supply Unit) modules (up-to two of them) for HA
* UPS((Uninterruptible Power Supply) to drain the data in case of power failure and to keep the RAM refreshed to avoid dataloss
* Redis Core (FPGA) modules

h2. BMC/IPMI/Redfish

It has to embed an onboard BMC/IPMI for easy management with its own dedicated NIC. 
Maybe OpenBMC (https://github.com/openbmc) running on a Raspberry Compute Module 3+ (https://www.raspberrypi.com/products/compute-module-3-plus/) in a SO-DIMM form factor, with a dedicated ENC28J60 NIC (https://www.raspberrypi.com/documentation/computers/compute-module.html).

h2. Power control and Reset

A Reset+Brown-out+Watchdog dedicated circuit
A clean reset momentary push button with NE555 debounce.
A momentary push power button (short press soft-toggles power, long press to hard power-off)

h2. I2C BUS

h3. RTC

with battery (or super-capa), updated by the microcontrolers, from the network, with NTP

h3. PWM FAN controlers

h1. FPGA node

[[FPGA node|FPGA node hardware design]]

h1. Microcontroler nodes

It has 1 (or 2 for HA) hotpluggable microcontroler module. Each of them has his own dedicated NIC(Network Interface Controler), as an 100M/1G/10G SFP+ module. It has to support backup and restore processes. With ATSHA, EEPROM, Flash, Clock, I2C BUS, I2C temp sensor