Document Scope
Purpose:
This document provides instructions for resetting the Baseboard Management Controller (BMC) on a Linux system using the ipmitool utility.
Background
The BMC (Baseboard Management Controller) is a specialized microcontroller embedded in most server-grade motherboards. It manages system monitoring (temperature, voltage, fan speeds) and enables remote management features like IPMI, KVM-over-IP, and remote power control.
Occasionally, the BMC may become unresponsive or require a reset after configuration changes, firmware updates, or system faults. Resetting the BMC clears temporary issues without rebooting the main server.
Requirements
- ipmitool package installed on the server
- Root or sudo access to execute IPMI commands
- Access to the local BMC (over ipmitool's local interface)
Installation of ipmitool (if needed)
On RHEL/CentOS/Rocky Linux systems:
sudo yum install ipmitool
On Ubuntu/Debian systems:
sudo apt install ipmitool
Resetting the BMC
1. Verify Access to the BMC
First, ensure you can communicate with the BMC:
You should see output containing BMC firmware revision, manufacturer ID, etc. If this fails, verify your system’s IPMI driver is loaded (moprobe ipmi_si)
2. Issue the BMC Reset Command
Run the following command to perform a soft reset:
sudo ipmitool mc reset warm
- warm reset will restart the BMC controller without interrupting or rebooting the host server.
If a warm reset doesn't clear your problem, you can attempt a cold reset (harder reset, more disruptive):
sudo ipmitool mc reset cold
-
Cold reset will reinitialize the BMC hardware more aggressively but still does not reboot the server itself.
⚠️ Important Notes
-
Some BMC resets may cause temporary disconnection from remote management interfaces (IPMI/iKVM/Redfish sessions).
-
Network interfaces controlled by the BMC (e.g., dedicated IPMI LAN ports) may briefly reset.
-
Always prefer a warm reset first unless otherwise instructed by your hardware vendor.
Verifying BMC Reset
After about 30–60 seconds, recheck the BMC status:
sudo ipmitool mc info
If you see a response, the BMC has restarted successfully.
Example Session
root@benchmark-svr:# ipmitool mc info
Device ID : 32
Device Revision : 1
Firmware Revision : 1.01
IPMI Version : 2.0
Manufacturer ID : 2623
Manufacturer Name : Unknown (0xA3F)
Product ID : 4499 (0x1193)
Product Name : Unknown (0x1193)
Device Available : yes
Provides Device SDRs : yes
Troubleshooting
If you encounter issues:
-
Check that ipmi_si and ipmi_devintf kernel modules are loaded.
-
Check
dmesg
orjournalctl -xe
for IPMI-related error logs. -
Verify no firewall or network configuration is blocking local IPMI communication.
✅ Conclusion
Resetting the BMC with ipmitool is a safe and effective way to resolve many remote management problems without disrupting server operations. Always try a warm reset first, and escalate to a cold reset only if necessary.
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