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Oracle® VM Server for SPARC 3.6 Administration Guide

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Updated: September 2019
 
 

Resource Reconfiguration

A system that runs the Oracle VM Server for SPARC software is able to configure resources, such as virtual CPUs, virtual I/O devices, and memory. Some resources can be configured dynamically on a running domain, while others must be configured on a stopped domain. If a resource cannot be dynamically configured on the control domain, you must first initiate a delayed reconfiguration. The delayed reconfiguration postpones the configuration activities until after the control domain has been rebooted.

Dynamic Reconfiguration

Dynamic reconfiguration (DR) enables resources to be added or removed while the operating system (OS) is running. The capability to perform DR of a particular resource type is dependent on having support in the OS running in the logical domain.

To use the DR capability, the Logical Domains DR daemon, drd, must be running in the domain that you want to change. See the drd(8) man page.

Delayed Reconfiguration

    In contrast to DR operations that take place immediately, delayed reconfiguration operations take effect in the following circumstances:

  • After the next reboot of the OS

  • After a stop and start of a logical domain if no OS is running

In general, delayed reconfiguration operations are restricted to the control domain. For all other domains, you must stop the domain to modify the configuration unless the resource can be dynamically reconfigured.

Delayed reconfiguration operations are restricted to the control domain. You can run a limited number of commands while a delayed reconfiguration on the root domain is in progress to support operations that cannot be completed dynamically. These subcommands are add-io, set-io, remove-io, create-vf, and destroy-vf. You can also run the ldm start-reconf command on the root domain. For all other domains, you must stop the domain to modify the configuration unless the resource can be dynamically reconfigured.

While a delayed reconfiguration is in progress, other reconfiguration requests for that domain are deferred until it is rebooted or stopped and started.

The ldm cancel-reconf command cancels delayed reconfiguration operations on the domain. For more information about how to use the delayed reconfiguration feature, see the ldm(8) man page.


Note - You cannot use the ldm cancel-reconf command if any other ldm remove-* commands have already performed a delayed reconfiguration operation on virtual I/O devices. The ldm cancel-reconf command fails in this circumstance.

You can use delayed reconfiguration to decrease resources on the control domain. To remove a large number of CPUs from the control domain, see Removing a Large Number of CPUs From a Domain Might Fail. To remove large amounts of memory from the control domain, see Decrease the Control Domain's Memory.


Note - When the primary domain is in a delayed reconfiguration state, resources that are managed by Oracle VM Server for SPARC are power-managed only after the primary domain reboots. Resources that are managed directly by the OS, such as CPUs that are managed by the Solaris Power Aware Dispatcher, are not affected by this state.

Only One CPU Configuration Operation Is Permitted to Be Performed During a Delayed Reconfiguration

Do not attempt to perform more than one CPU configuration operation on the primary domain while it is in a delayed reconfiguration. If you attempt more CPU configuration requests, they will be rejected.

Workaround: Perform one of the following actions:

  • Cancel the delayed reconfiguration, start another one, and request the configuration changes that were lost from the previous delayed reconfiguration.

  • Reboot the control domain with the incorrect CPU count and then make the allocation corrections after the domain reboots.