Chassis Status

The ChassisStatus object

try (IpmiClient bmc = IpmiClient.builder(host).credentials(user, password).build()) {
	ChassisStatus status = bmc.chassisStatus();

	System.out.println("Power: " + (status.powerOn() ? "on" : "off"));
	System.out.println("Restore policy: " + status.powerRestorePolicy());
	System.out.println("Intrusion: " + status.intrusion());
}

ChassisStatus^[1] decodes the response (IPMI 2.0, section 28.2) and never throws:

Not every BMC fills every flag: the intrusion, drive and cooling bits in particular are optional in the specification, and a BMC that does not implement them reports false.

Controlling the power

chassisControl(PowerCommand) sends the Chassis Control command (IPMI 2.0, section 28.3). It needs a client built with the Operator or Administrator privilege^[4], which the client requests at login and sets right after it (Set Session Privilege Level): at the default User level the BMC refuses the command with D4h, and an account not allowed Operator fails the first operation with IpmiAuthenticationException.

try (IpmiClient bmc = IpmiClient.builder(host).credentials(user, password)
		.privilege(PrivilegeLevel.Operator).build()) {
	if (!bmc.chassisStatus().powerOn()) {
		bmc.chassisControl(PowerCommand.PowerUp);
	}
}

The BMC answers as soon as it accepts the command, and carries it out afterwards: a power off takes a few seconds, a soft shutdown as long as the operating system needs. Poll chassisStatus().powerOn() to see the state change. A refused command fails with IpmiCompletionCodeException^[5]: D4h at a session below Operator, D5h for a command the system's present state does not allow, CCh for an optional command the BMC does not implement.

Unlike the read operations, a control command is sent once: not again when its reply is lost or is a C3h (a timeout on the BMC side, which says the response is unavailable, not that nothing was done), since the BMC may have carried it out and a second reset would reset the system twice, and not on a new session. A lost reply fails with IpmiTimeoutException, a C3h with IpmiCompletionCodeException, and chassisStatus() then tells what the BMC did; a busy BMC (C0h), which did nothing, is retried as for any command. PowerCycle is refused with IllegalStateException, before anything is sent, when the system is off: the specification recommends that check, as some BMCs power the system up instead of doing nothing.

The identify LED

chassisIdentify(int seconds) sends the Chassis Identify command (IPMI 2.0, section 28.5): the chassis identifies itself, typically by blinking a LED, for the given number of seconds (1 to 255; the BMC may stretch it by 20%). chassisIdentify(0) turns the identify off, and chassisIdentifyForever() keeps it on until then, with the optional “force identify on” byte of the command, which not every BMC implements (CCh from those that do not). Both need the Operator privilege, are sent once like the power commands, and identifyState() of the chassis status reports the result on the BMCs that support it:

bmc.chassisIdentify(30);
System.out.println(bmc.chassisStatus().identifyState()); // Optional[TemporaryOn]
bmc.chassisIdentify(0);