Managing Power in Cisco UCS

This chapter includes the following sections:

•

Power Management in Cisco UCS , page 1

•

Rack Server Power Management, page 1

•

Power Management Precautions, page 1

•

Configuring the Power Policy, page 2

•

Configuring the Global Cap Policy, page 3

•

Configuring Policy-Driven Chassis Group Power Capping, page 3

•

Configuring Manual Blade-Level Power Capping, page 10

Power Management in Cisco UCS

You can manage power through Cisco UCS Manager by configuring any of the following features:

•

Power supply redundancy for all chassis in a Cisco UCS domain

•

Policy-driven chassis-level power capping

•

Manual blade-level power capping

Rack Server Power Management

Power capping is not supported for rack servers.

Power Management Precautions

If the CIMC is reset, the power monitoring functions of Cisco UCS become briefly unavailable for as long

as it takes for the CIMC to reboot. While this usually only takes 20 seconds, there is a possibility that the peak

power cap could be exceeded during that time. To avoid exceeding the configured power cap in a very low

power-capped environment, consider staggering the rebooting or activation of CIMCs.

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Configuring the Power Policy

Power Policy

The power policy is a global policy that specifies the redundancy for power supplies in all chassis in the Cisco

UCS domain. This policy is also known as the PSU policy.

For more information about power supply redundancy, see Cisco UCS 5108 Server Chassis Hardware

Installation Guide.

Configuring the Power Policy

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, click the Equipment node.

Step 3

In the Work pane, click the Policies tab.

Step 4

Click the Global Policies subtab.

Step 5

In the Power Policy area, click one of the following radio buttons in the Redundancy field:

• Non Redundant—Cisco UCS Manager turns on the minimum number of power supplies (PSUs) needed

and balances the load between them. If any additional PSUs are installed, Cisco UCS Manager sets them

to a "turned-off" state. If the power to any PSU is disrupted, the system may experience an interruption

in service until Cisco UCS Manager can activate a new PSU and rebalance the load.

In general, a Cisco UCS chassis requires at least two PSUs for non redundant operation. Only smaller

configurations (requiring less than 2500W) can be powered by a single PSU.

• N+1—The total number of PSUs to satisfy non-redundancy, plus one additional PSU for redundancy,

are turned on and equally share the power load for the chassis. If any additional PSUs are installed, Cisco

UCS Manager sets them to a "turned-off" state. If the power to any PSU is disrupted, Cisco UCS Manager

can recover without an interruption in service.

In general, a Cisco UCS chassis requires at least three PSUs for N+1 operation.

• Grid—Two power sources are turned on, or the chassis requires greater than N+1 redundancy. If one

source fails (which causes a loss of power to one or two PSUs), the surviving PSUs on the other power

circuit continue to provide power to the chassis.

For more information about power supply redundancy, see Cisco UCS 5108 Server Chassis Hardware

Installation Guide.

Step 6

Click Save Changes.

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Configuring the Power Policy

Configuring the Global Cap Policy

Global Cap Policy

The global cap policy is a global policy that specifies whether policy-driven chassis group power capping or

manual blade-level power capping will be applied to all servers in a chassis.

We recommend that you use the default power capping method: policy-driven chassis group power capping.

Any change to the manual blade-level power cap configuration will result in the loss of any groups or

configuration options set for policy-driven chassis group power capping.

Important

Configuring the Global Cap Policy

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, click the Equipment node.

Step 3

In the Work pane, click the Policies tab.

Step 4

Click the Global Policies subtab.

Step 5

In the Global Cap Policy area, click one of the following radio buttons in the Allocation Method field to

determine the power cap management mode used in the Cisco UCS domain:

• Manual Blade Level Cap—Power allocation is configured on each individual blade server in all chassis.

If you select this option, you cannot create power groups.

• Policy Driven Chassis Group Cap—Power allocation is configured at the chassis level through power

control policies included in the associated service profiles. If you select this option, you can also create

power groups that contain one or more chassis in the Cisco UCS domain.

By default, power allocation is done for each chassis through a power control policy.

Step 6

Click Save Changes.

Configuring Policy-Driven Chassis Group Power Capping

Policy-Driven Chassis Group Power Capping

When policy-driven power chassis group power capping is selected in the global cap policy, Cisco UCS can

maintain the oversubscription of servers without risking costly power failures. This is achieved through a

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two-tier process. At the chassis level, Cisco UCS divides the amount of power available between members

of the power group. At the blade level, the amount of power allotted to a chassis is divided between blades

based on priority.

Each time a service profile is associated or disassociated, UCS Manager recalculates the power allotment for

each blade server within the chassis. If necessary, power from lower-priority service profiles is redistributed

to higher-priority service profiles.

UCS power groups cap power in less than one second in order to safely protect data center circuit breakers.

A blade must stay at its cap for 20 seconds before the chassis power distribution is optimized. This is

intentionally carried out over a slower timescale to prevent reacting to transient spikes in demand.

The system reserves enough power to boot a server in each slot, even if that slot is empty. This reserved

power cannot be leveraged by servers requiring more power. Blades that fail to comply with the power

cap are penalized or shut down.

Note

Configuring Power Groups

Power Groups

A power group is a set of chassis that all draw power from the same power distribution unit (PDU). In Cisco

UCS Manager, you can create power groups that include one or more chassis and then set a peak power cap

in AC watts for that power grouping.

Instituting power capping at the chassis level requires the following:

•

IOM, CIMC, and BIOS version 1.4 or higher

•

2 PSUs

The peak power cap is a static value that represents the maximum power available to all blade servers within

a given power group. If you add or remove a blade from a power group, but do not manually modify the peak

power value, the power group adjusts the peak power cap to accommodate the basic power-on requirements

of all blades within that power group.

A minimum of 1556 AC watts should be set for each chassis. This converts to 1400 watts of DC power, which

is the minimum amount of power required to power a fully-populated chassis.

Once a chassis is added to a power group, every service profile associated with the blades in the chassis also

becomes part of that power group. Similarly, if you add a new blade to a chassis, that blade inherently becomes

part of the chassis' power group.

Creating a power group is not the same as creating a server pool. However, you can populate a server pool

with members of the same power group by creating a power qualifier and adding it to server pool policy.

Note

When a chassis is removed or deleted, the chassis gets removed from the power group.

The following table describes the error messages you might encounter while assigning power budget and

working with power groups.

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Recommended ActionCauseError Message

Increase the power cap limit to

above 1556 watts in AC (1400

watts in DC).

This message is displayed if you

did not meet the minimum limit

when assigning the power cap for

a chassis.

Insufficient budget for

power group

POWERGROUP_NAME

You can reassign the power budget

by doing one of the following:

•

Remove or decommission a

chassis or blade in the power

group.

•

Raise the group power

budget.

•

Decrease the priority

associated with a blade in the

group.

This message is displayed when

you introduce a new blade and the

boot power available for blade

discovery is insufficient.

Insufficient power

available to discover

server Chassis

ID/BladeID

Creating a Power Group

Before You Begin

Make sure the global power allocation policy is set to Policy Driven Chassis Group Cap on the Global

Policies tab.

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, click the Equipment node.

Step 3

In the Work pane, click the Policies tab.

Step 4

Click the Power Groups subtab.

Step 5

On the icon bar to the right of the table, click +.

If the + icon is disabled, click an entry in the table to enable it.

Step 6

On the first page of the Create Power Group wizard, complete the following fields:

a) Enter a unique name and description for the power group.

This name can be between 1 and 16 alphanumeric characters. You cannot use spaces or any special

characters other than - (hyphen), _ (underscore), : (colon), and . (period), and you cannot change this name

after the object has been saved.

b) Click Next.

Step 7

On the Add Chassis Members page of the Create Power Group wizard, do the following:

a) In the Chassis table, choose one or more chassis to include in the power group.

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b) Click the >> button to add the chassis to the Selected Chassis table that displays all chassis included in

the power group.

You can use the << button to remove one or more chassis from the power group.

c) Click Next.

Step 8

On the Power Group Attributes page of the Create Power Group wizard, do the following:

a) Complete the following fields:

DescriptionName

The maximum peak power (in watts) available to the power group.

Enter an integer between 0 and 10000000.

Power Cap field

This can be one of the following:

• Chassis—Cisco UCS monitors power usage and changes the

blade allocations as required to maximize power utilization.

• None—Blade allocations are not adjusted dynamically.

Enable Dynamic Reallocation

field

b) Click Finish.

Adding a Chassis to a Power Group

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, click the Equipment node.

Step 3

In the Work pane, click the Power Groups tab.

Step 4

Right-click the power group to which you want to add a chassis and choose Add Chassis Members.

Step 5

In the Add Chassis Members dialog box, do the following:

a) In the Chassis table, choose one or more chassis to include in the power group.

b) Click the >> button to add the chassis to the Selected Chassis table that displays all chassis included in

the power group.

You can use the << button to remove one or more chassis from the power group.

c) Click OK.

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Removing a Chassis from a Power Group

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, click the Equipment node.

Step 3

In the Work pane, click the Power Groups tab.

Step 4

Expand the power group from which you want to remove a chassis.

Step 5

Right-click the chassis that you want to remove from the power group and choose Delete.

Step 6

If the Cisco UCS Manager GUI displays a confirmation dialog box, click Yes.

Deleting a Power Group

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, click the Equipment node.

Step 3

In the Work pane, click the Power Groups tab.

Step 4

Right-click the power group that you want to delete and choose Delete.

Step 5

If the Cisco UCS Manager GUI displays a confirmation dialog box, click Yes.

Configuring Power Control Policies

Power Control Policy

Cisco UCS uses the priority set in the power control policy, along with the blade type and configuration, to

calculate the initial power allocation for each blade within a chassis. During normal operation, the active

blades within a chassis can borrow power from idle blades within the same chassis. If all blades are active

and reach the power cap, service profiles with higher priority power control policies take precedence over

service profiles with lower priority power control policies.

Priority is ranked on a scale of 1-10, where 1 indicates the highest priority and 10 indicates lowest priority.

The default priority is 5.

For mission-critical application a special priority called no-cap is also available. Setting the priority to no-cap

prevents Cisco UCS from leveraging unused power from a particular server. With this setting, the server is

allocated the maximum amount of power possible for that type of server.

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You must include this policy in a service profile and that service profile must be associated with a server

for it to take effect.

Note

Creating a Power Control Policy

Procedure

Step 1

In the Navigation pane, click the Servers tab.

Step 2

On the Servers tab, expand Servers > Policies.

Step 3

Expand the node for the organization where you want to create the policy.

If the system does not include multitenancy, expand the root node.

Step 4

Right-click Power Control Policies and choose Create Power Control Policy.

Step 5

In the Create Power Control Policy dialog box, complete the following fields:

DescriptionName

The name of the policy.

This name can be between 1 and 16 alphanumeric characters. You

cannot use spaces or any special characters other than - (hyphen), _

(underscore), : (colon), and . (period), and you cannot change this name

after the object has been saved.

Name field

A description of the policy. We recommend that you include information

about where and when the policy should be used.

Enter up to 256 characters. You can use any characters or spaces except

` (accent mark), \ (backslash), ^ (carat), " (double quote), = (equal sign),

> (greater than), < (less than), or ' (single quote).

Description field

This can be one of the following:

• Local—This policy is available only to service profiles and service

profile templates in this Cisco UCS domain.

• Pending Global—Control of this policy is being transferred to

Cisco UCS Central. Once the transfer is complete, this policy will

be available to all Cisco UCS domains registered with Cisco UCS

Central.

• Global—This policy is managed by Cisco UCS Central. Any

changes to this policy must be made through Cisco UCS Central.

Owner field

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DescriptionName

What happens to a server when the demand for power within a power

group exceeds the power supply. This can be one of the following:

• No Cap—The server runs at full capacity regardless of the power

requirements of the other servers in its power group.

• cap—The server is allocated a minimum amount of power capacity

based on the the server's priority relative to the other servers in its

server group. If more power becomes available, Cisco UCS allows

the capped servers to exceed their original allocations. It only

lowers the allocations if there is a drop in the total power available

to the power group.

When you select cap, Cisco UCS Manager GUI displays the Priority

field.

Power Capping field

The priority the server has within its power group when power capping

is in effect.

Enter an integer between 1 and 10, where 1 is the highest priority.

Priority field

Step 6

Click OK.

What to Do Next

Include the policy in a service profile or service profile template.

Deleting a Power Control Policy

Procedure

Step 1

In the Navigation pane, click the Servers tab.

Step 2

On the Servers tab, expand Servers > Policies > Organization_Name.

Step 3

Expand the Power Control Policies node.

Step 4

Right-click the policy you want to delete and select Delete.

Step 5

If the Cisco UCS Manager GUI displays a confirmation dialog box, click Yes.

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Configuring Manual Blade-Level Power Capping

Manual Blade-Level Power Capping

When manual blade-level power capping is configured in the global cap policy, you can set a power cap for

each blade server in a Cisco UCS domain.

The following configuration options are available:

Enabled

You can specify the maximum amount of power that the server can consume at one time. This maximum

can be any amount between 0 watts and 1100 watts.

Disabled

No power usage limitations are imposed upon the server. The server can use as much power as it

requires.

If the server encounters a spike in power usage that meets or exceeds the maximum configured for the server,

Cisco UCS Manager does not disconnect or shut down the server. Instead, Cisco UCS Manager reduces the

power that is made available to the server. This reduction can slow down the server, including a reduction in

CPU speed.

If manual blade-level power capping is configured using Equipment > Policies > Global Policies >

Global Power Allocation Policy, the priority set in the Power Control Policy is no longer relevant .

Note

Setting the Blade-Level Power Cap for a Server

Before You Begin

Make sure the global power allocation policy is set to Manual Blade Level Cap on the Global Policies tab.

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, expand Equipment > Chassis > Chassis Number > Servers.

Step 3

Choose the server for which you want to set the power budget.

Step 4

In the Work pane, click the General tab.

Step 5

In the Power Budget area, do the following:

a) Click the Expand icon to the right of the heading to display the fields.

b) Complete the following fields:

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DescriptionName

Whether this server is power capped. This can be one of the following:

• Unbounded—The server is not power capped under any

circumstances.

• Enabled—Cisco UCS Manager GUI displays the Watts field.

Power capping only goes into effect if there is insufficient

power available to the chassis to meet the demand. If there

is sufficient power, the server can use as many watts as it

requires.

Note

Admin Status field

The maximum number of watts the server can use if there is not

enough power to the chassis to meet the demand.

Enter an integer between 0 and 10000000.

Watts field

Step 6

Click Save Changes.

Viewing the Blade-Level Power Cap

Procedure

Step 1

In the Navigation pane, click the Equipment tab.

Step 2

On the Equipment tab, expand Equipment > Chassis.

Step 3

Choose the chassis for which you want to view the server power usage.

Step 4

Do one of the following:

•

To view the power usage for all servers in the chassis, click the Power tab in the Work pane.

•

To view the power usage for one server in the chassis, expand the chassis and click the server. Then

click the Power tab in the Work pane.

Step 5

If necessary, expand the Motherboards node to view the power counters.

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