VIOS configuration and tuning for optimum partition mobility performance

To achieve good partition mobility performance, you must ensure that system resources, particularly the Virtual I/O Server (VIOS) resources are appropriately configured and tuned. By following the configuration details that are listed in this topic for various VIOS components, you can improve the partition mobility performance.

The configurations that are listed in this topic for partition mobility assume that the VIOS has already been configured for good virtual I/O performance by running the VIOS Advisor and implementing any changes that were proposed by the VIOS Advisor.

From VIOS Version or later, and when you are not using secure Live Partition Mobility, you can avoid the overhead of checking the secure IP tunnel setup by setting the auto_tunnel attribute value. To set the attribute value, run the following command from the VIOS command line:
chdev –dev  vioslpm0 –attr auto_tunnel=0

You can set the value of the max_virtual_slots attribute to a value of 4000 or less, unless you require a higher value to support a large number of virtual devices.


Use the processor resource settings that are specified in the following table for optimum partition mobility performance, in addition to the resources that are already assigned to the VIOS for managing the existing virtual I/O requirements:
Table 1. Concurrent migrations
Scenario POWER7®

Dedicated cores or Shared processor (or vCPUs)


Dedicated cores or Shared processor (or vCPUs)


Dedicated cores or Shared processor (or vCPUs)

Maximum number of concurrent migration operations on a 40-Gigabit Ethernet 5 4 3
Maximum number of concurrent migration operations on 10-Gigabit Ethernet 4 3 2
1-Gigabit Ethernet, or other applications on 10 Gigabit Ethernet link or links for Live Partition Mobility already use close to 100% of the bandwidth 1 1 1

When you are using 1-Gigabit Ethernet or if the bandwidth of the 10-Gigabit Ethernet link or links to be used for Live Partition Mobility already reaches peaks of near 100% usage, you need only 1 more POWER7, POWER7+, or POWER8 core or shared processor (or vCPUs), regardless of the number of concurrent migrations.

When you are using shared processors for the VIOS and you need to increase the number of shared processors (or vCPUs), you must ensure that the corresponding amount of computing capacity is available in the shared pool.

For consistent partition mobility performance, you can disable the power saver mode to ensure that the processor clock frequency remains constant at the nominal value.


No additional memory is required for performing partition mobility operations apart from the general memory requirements for the VIOS.


Although partition mobility operations can run over a Shared Ethernet Adapter (SEA), to optimize performance, you can use a dedicated physical adapter or EtherChannel.

The large send and large receive offload (LRO) attributes must be enabled on all network interfaces and devices. However, these attributes must not be set when the partition is an AIX® or Linux partition because of interoperability issues with these operating systems.

If your network environment supports jumbo frames, jumbo frames (9000-byte MTU) is recommended especially on high speed networks.

For EtherChannel configurations, the EtherChannel mode attributes must be set to standard and the hash_mode attribute must be set to src_dst_port or src_port, where src_dst_port is the recommended value.

Last updated: Tue, March 12, 2019