Enabling pcie power override – HP MSR Encryption Accelerators User Manual

Page 36

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Maintenance 36

fio-update-iodrive

For more information, see "Utilities reference (on page

40

)."

Enabling PCIe power override

For PCIe IO Accelerators, if you have installed any dual IO Accelerator devices, such as the HP ioDrive2

Duo, then the device might require additional power than the minimum 25 W provided by PCIe Gen2 slots

to properly function. Even if additional power is not required for your device, all dual IO Accelerator devices

that receive additional power might benefit with improved performance.
HP ioDrive2 Duo devices must have additional power to properly function. For more information on which

devices require additional power, see the HP PCIe IO Accelerator for ProLiant Servers Installation Guide.
Additional power can be provided in two ways:

External power cable—This cable ships with all dual ioMemory devices. For information on installing
this cable, see the HP PCIe IO Accelerator for ProLiant Servers Installation Guide.

NOTE:

When a power cable is used, all of the power is drawn from the cable and no power is

drawn from the PCIe slot.

Enabling full slot power draw—Some PCIe slots provide additional power (often up to 75 W of power).

If your PCIe slot is rated to provide at least 55 W, then you can allow the device to draw full power from
the PCIe slot by setting a VSL module parameter. For more information on enabling this override

parameter, see "Enabling the override parameter (on page

37

)."

CAUTION:

If the PCIe slot is not capable of providing the needed amount of power, then

enabling full power draw from the PCIe slot might result in malfunction or even damage to server

hardware. The user is responsible for any damage to equipment due to improper use of the
override parameter. HP expressly disclaims any liability for damage arising from improper use of

the override parameter. To confirm the power limits and capabilities of each slot, as well as the

entire system, contact the server manufacturer. For information about using the override

parameter, contact HP Customer Support.

NOTE:

The override parameter overrides the setting that prevents devices from drawing more

than 25 W from the PCIe slot. The parameter is enabled by device using the device serial

numbers. Once the setting is overridden, each device might draw up to the full 55 W needed for
peak performance.

Before you enable the override parameter, ensure that each PCIe slot is rated to provide enough power
for all slots, devices, and server accessories. To determine the power slot limits, consult the server
documentation, BIOS interface, setup utility, or use the fio-pci-check command.

Important considerations

If you are installing more than one dual IO Accelerator device and enabling the override parameter for
each device, be sure the motherboard is rated to provide 55W power to each slot used. For example,

some motherboards safely provide up to 75W to any one slot, but run into power constraints when
multiple slots are used to provide that much power. Installing multiple devices in this situation might

result in server hardware damage. Consult with the manufacturer to determine the total PCIe slot power

available.

The override parameter persists in the system and enables full power draw on an enabled device even
if the device is removed and then placed in a different slot within the same system. If the device is placed

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