ISS Technology Update, Vol. 7 Number 6

ISS Technology Update Volume 7, Number 6
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y Update
Volume 7, Number 3
Keeping you informed of the latest ISS technology
Quick Tips
Recommendations for powering off/on HP BladeSystem c7000 enclosures and their
components
During planned data center shutdowns, what is the best way to power down c7000 enclosures with
minimal manual intervention?
The Onboard Administrator (OA) is the heart of c-Class enclosure management and one of its most important tasks is power
control. The OA allows you to remotely power down all blade servers and interconnects in BladeSystem c7000 enclosures. For
components in device bays in the front of each enclosure, the OA communicates with iLO 2 to control servers. The OA also
communicates with a microcontroller to control options, such as storage blades. A separate microcontroller controls power to
interconnect modules.
You could also connect all components in the enclosure to an intelligent Power Distribution Unit (PDU). PDUs typically have
multiple outlets and a single power cord that terminates with a plug. By connecting the devices’ power cords to an intelligent
PDU, you can remotely power off all devices in the enclosure.
When powering down, can I leave all power cables connected?
Yes. You can leave all power cables connected after AC input power is removed.
Will switch configurations be preserved when the enclosure is powered down?
Yes. The OA and all interconnect switch modules save their configurations in non-volatile memory. They restore those saved
configurations when the AC power returns.
What happens when AC power returns after a planned power outage? Will the OA and interconnect
switches power themselves in the correct order?
When the enclosure is powered on, the goal of the OA is to minimize power surge. If iLO 2 is configured on each server to
enable auto power-on (default factory setting), then the sequence of events is as follows:
The fans start up in fail-safe mode before the OA boots because the fans are unaware of the equipment installed in the
enclosure. When the OA boots, it takes control and slows the fans’ speed. Then the OA figures out the devices installed in the
enclosure and powers up the interconnects sequentially, starting at module 1, unless the user has enabled power delay for any
of the components.
Next, the iLO 2 uses auxiliary power to make a power request for each server blade based on the configuration of the iLO 2
auto power-on setting. If this setting is disabled, the server must be manually powered on following a power cycle to the entire
enclosure. Because each ILO 2 is unaware of the actual server configuration, it requests power from the OA based on its
maximum possible configuration. The OA calculates the total power available to the enclosure based on the number of power
supplies and the user-selected power redundancy mode. As OA receives each power request, it subtracts that amount from the
remaining power available. When the remaining power is less than that requested by a server, the OA denies the power to that
server. As the blades with power go through POST, each server’s iLO 2 adjusts its power request to OA to more accurately
reflect the maximum server power consumption. This process allows OA to readjust the power available for other servers to
power on. The power readjustment process by the OA is the reason that the last few servers can take some time to power on.
The Onboard Administrator (v2.20 firmware and higher) has the ability to be configured to provide a user configurable power
delay for each interconnect and server power-on after the entire enclosure has been power cycled. This feature allows the user
to delay server power-on until the interconnect modules have had time to complete their POST, so that Ethernet and FC
connections are available as the server is powered on. The feature also ensures that servers providing key services, such as
DNS or DHCP, can power up before the other servers.