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This document describes the required power-on and power-off procedures for the SambaRack SN40L-16 rack. Correct power sequencing prevents hardware damage and ensures reliable operation. For routine operations, use SambaRack Manager to control node power individually or in groups. See Node management or Group management.

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Safety warnings

Review and observe the following safety requirements before performing any power operations.
High voltage is present within the rack. To prevent injury and warranty violations, do not service components except where explicitly noted.
  • Rack doors: Keep front and rear doors closed during operation to protect components.
  • Airflow: Keep the front and rear of the rack clear of obstructions to ensure adequate cooling.
  • Firmware updates: Do not power off or reboot components during firmware updates. Wait until all updates complete.

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Power sequence summary

The following summaries show the required order for power-on and power-off operations. Detailed procedures are provided in subsequent sections.

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Power-on order

Power on components in the following sequence:
  1. Core Services Rack
    • Turn on PDU circuit breakers
    • Boot SMS and Control Plane servers
  2. SambaRack SN40L-16
    • Turn on PDU circuit breakers
    • Boot SN40L-2 RDU modules
    • Boot SN40L-H host module

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Power-off order

Power off components in the following sequence:
  1. SambaRack SN40L-16
    • Shut down SN40L-H host module
    • Shut down SN40L-2 RDU modules
  2. Network devices (in order)
    • Juniper QFX5130 data switch
    • Lantronix SLC8000 serial console server
    • Juniper EX series access switch (last)

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Power-on procedures

Complete the following steps after initial installation or a full power-down.

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Step 1: Enable PDU circuit breakers

Turn on all six circuit breakers on each PDU. When the breakers close, power is applied to all rack components automatically.
PDU circuit breaker group. Breaker switch 6 is circled. Each PDU contains six grouped breakers. After breakers are enabled, components enter the following states:
ComponentState
SN40L-H host moduleStandby (BMC powered, awaiting manual power-on)
SN40L-2 RDU modulesStandby (BMC powered, awaiting manual power-on)
Network equipmentFully booted
The Juniper QFX5130 port 16 displays an amber light. This is expected and does not indicate a fault.
If SambaRack Manager is installed, use it to complete the power-on sequence. See the Power on section in Node management. If SambaRack Manager is unavailable, continue with Steps 3 and 4.

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Step 3: boot SN40L-2 RDU modules

This step powers on the SN40L-2 RDU modules, which must be fully operational before starting the host module.
Boot all SN40L-2 RDU modules before powering on the SN40L-H host module.
IP addresses are documented in your customer-specific IP assignment worksheet. Contact your administrator if needed.
Choose one of the following methods: Option A: SSH Use SSH to connect to the BMC and run power commands. Prerequisites:
  • Access to the rack management network
Procedure:
  1. Connect to the first SN40L-2 RDU module:
ssh root@<SN40L-2_BMC_IP>
  1. Power on all RDU modules:
xrduutil -U root -P <root_password> poweron
  1. Verify power state before proceeding:
xrduutil -U root -P <root_password> powerstate
Expected output: 
Power is on for XRDU_0
Power is on for XRDU_1
Power is on for XRDU_2
Power is on for XRDU_3
Power is on for XRDU_4
Power is on for XRDU_5
Power is on for XRDU_6
Power is on for XRDU_7
Option B: REST API Use the OpenBMC REST API to send power commands remotely. Prerequisites:
  • Access to the rack management network
  • Authentication token generated
SambaNova recommends token-based authentication. See Generate a secure API login token for details.
Procedure:
  1. Send the power-on command to each SN40L-2 RDU module (any order):
curl -b cjar -k -H "X-Auth-Token: $token" -X PUT \
  -d '{"data":"xyz.openbmc_project.State.Chassis.Transition.On"}' \
  https://<SN40L-2_BMC_IP>/xyz/openbmc_project/state/chassis0/attr/RequestedPowerTransition
  1. Verify power state before proceeding:
curl -b cjar -k -H "X-Auth-Token: $token" \
  https://<SN40L-2_BMC_IP>/xyz/openbmc_project/state/chassis0
Expected output: 
{
  "data": {
    "CurrentPowerState": "xyz.openbmc_project.State.Chassis.PowerState.On",
    "LastStateChangeTime": 1591197275103,
    "POHCounter": 75,
    "RequestedPowerTransition": "xyz.openbmc_project.State.Chassis.Transition.On"
  },
  "message": "200 OK",
  "status": "ok"
}
Option C: Physical power button Use the front panel power button to manually power on each module. Procedure:
  1. Locate the power button on the front left panel (item 1 in the figure below).
  2. Press and hold for 5 seconds.
  3. Wait for the system LED (item 2) to change from blinking to solid green (up to one minute).
  4. Repeat for each SN40L-2 module in the node.
SN40L-2 front panel. Item 1: power button. Item 2: system LED.

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Step 4: Boot SN40L-H host module

This step powers on the host module after all RDU modules are operational.
Do not proceed until all SN40L-2 RDU modules are powered on.
Choose one of the following methods: Option A: Physical power button Use the front panel power button to manually power on the host module. Procedure:
  1. Press the power button on the front left panel of the SN40L-H.
SN40L-H front panel with power button location. Option B: IPMI Use IPMI to send power commands remotely via the BMC. Prerequisites:
  • ipmitool installed on your workstation
  • Access to BMC via access network
Procedure:
  1. Run the following command:
ipmitool -I lanplus -H <SN40L-H_BMC_IP> -U root -P <root_password> power on
Option C: Web UI Use the BMC web interface to power on the host module. Prerequisites:
  • Access to BMC via access network
  • Chrome or Firefox (latest version)
Procedure:
  1. Navigate to https://<SN40L-H_BMC_IP> in your browser.
  2. Log in and click Sign me in.
  3. Select Power Control from the dashboard.
  1. Select Power On, then click Perform Action.
  1. Repeat for all nodes in the rack (any order).

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Power-off procedures

Use SambaRack Manager for routine power-off operations. See Node operations. If SambaRack Manager is unavailable, complete the following steps in the order listed.

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Step 1: Shut down SN40L-H host module

This step gracefully shuts down the host module before powering off the RDU modules. Choose one of the following methods: Option A: Operating system Initiate a graceful shutdown from the operating system. Prerequisites:
  • SSH access to the node
Procedure:
  1. Connect to the node and run the shutdown command:
ssh snuser1@<SN40L-H_OS_IP>
sudo shutdown
The system waits approximately one minute before shutting down. Option B: IPMI Use IPMI to send a power-off command via the BMC. Prerequisites:
  • ipmitool installed on your workstation
  • Access to BMC via access network
Procedure:
  1. Run the following command:
ipmitool -I lanplus -H <SN40L-H_BMC_IP> -U root -P <root_password> power off
Option C: Web UI Use the BMC web interface to power off the host module. Prerequisites:
  • Access to BMC via access network
  • Chrome or Firefox (latest version)
Procedure:
  1. Navigate to https://<SN40L-H_BMC_IP> in your browser.
  2. Log in and click Sign me in.
  3. Select Power Control from the dashboard.
  4. Select Power Off, then click Perform Action.

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Step 2: Shut down SN40L-2 RDU modules

This step powers off the RDU modules after the host module is fully shut down.
Do not proceed until the SN40L-H host module is fully shut down.
Choose one of the following methods: Option A: SSH Use SSH to connect to the BMC and run power-off commands. Prerequisites:
  • Access to the rack management network
Procedure:
  1. Connect to the first SN40L-2 in each node:
ssh root@<SN40L-2_BMC_IP>
  1. Power off all RDU modules:
xrduutil -U root -P <root_password> poweroff
Option B: REST API Use the OpenBMC REST API to send power-off commands remotely. Prerequisites:
  • Access to the rack management network
  • Authentication token generated
Use token-based authentication. See Generate a secure API login token for details.
Procedure:
  1. Send the power-off command to each SN40L-2 RDU module:
curl -b cjar -k -H "X-Auth-Token: $token" -X PUT \
  -d '{"data":"xyz.openbmc_project.State.Chassis.Transition.Off"}' \
  https://<SN40L-2_BMC_IP>/xyz/openbmc_project/state/chassis0/attr/RequestedPowerTransition

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Step 3: Shut down network devices

This step powers off the network infrastructure. The access switch must be shut down last because it controls management network connectivity. Shut down network devices in the following order:
OrderDeviceNotes
1Juniper QFX5130 data switch—
2Lantronix SLC8000 serial console server—
3Juniper EX series access switchShut down last. Controls management network access.
Once the access switch is powered off, PDU outlets cannot be cycled remotely. To restore power, physically toggle the circuit breakers on the PDU.
See Third-party component documentation for device-specific shutdown procedures.