Planning for performance

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As you plan your IBM® Power® Virtualization Center environment, ensure that you adhere to the recommended hardware and software minimums and maximums to achieve the best possible performance.

Installing other software

It is recommended that PowerVC is the only server application hosted on the virtual machine. However, PowerVC can generally coexist with other software on the same instance, assuming that there is no resource or dependency conflict between PowerVC and the other software. Potential conflicts include port contention, user namespace, file system capacity, firewall settings, and so on. It is not recommended that you version lock any RPMs except when directed to do so by IBM support.

You should also consider performance implications to PowerVC and to the other software when installing other software on the same instance. For example, PowerVC memory usage may grow and cause problems with applications that coexist with PowerVC.

PowerVC resource requirements are sized assuming that PowerVC is the only workload that is running on the management instance. If other applications are using resources, adjust the sizing accordingly.

The following table lists some additional performance and scale considerations to observe to manage your PowerVC configuration with optimal performance.

Table 1. Performance and scale considerations to observe in your environment
Item	Requirement
Hardware and software requirements	Ensure that the hardware and software in your environment meets the requirements that are documented for PowerVC.
Maximum number of hosts and virtual machines (HMC)	A maximum of 30 HMC-managed hosts are supported. Each host can have a maximum of 1000 virtual machines on it. A maximum of 3000 virtual machines can be on all of the hosts combined. Each HMC can manage a maximum of 1000 virtual machines.
Maximum number of hosts and virtual machines (NovaLink)	A maximum of 50 NovaLink-managed hosts is supported. A maximum of 6000 virtual machines can be on all of the NovaLink-managed hosts combined. A maximum of 1000 virtual machines (NovaLink, Virtual I/O Servers, or client workloads) per PowerVM® host are supported. This limit is determined by the PowerVM platform firmware versions available when PowerVC version 1.4.4 was released. Refer to the IBM Redbook IBM PowerVM Best Practices for information about configuring your system for scale.
Mixed HMC and NovaLink scaling limits	When your environment consists of both HMC-managed and NovaLink-managed hosts A maximum of 3000 virtual machines can be on all of the hosts combined. A maximum of 50 hosts is supported of which 30 hosts can be HMC-managed.
Maximum number of virtual machines for each SAN Volume Controller	Each Storwize® V7000 control enclosure at version 6.4 can support a maximum of 256 virtual machines. Each Storwize V7000 control enclosure at version 7.1 can support a maximum of 512 virtual machines.
Maximum number of virtual resources	It is recommended that you configure the maximum number of virtual resources (virtual adapters) for the Virtual I/O Server to be at least three times the number of virtual machines that you plan to deploy on the host. This should enable you to have sufficient resources available on your hosts as you create and migrate virtual machines throughout your environment.
Number of concurrent deployment operations	PowerVC has the following limits on deployments: PowerVC supports a maximum of 50 concurrent deployments. Exceeding 8 concurrent deploys per host is not recommended. Running more than 10 concurrent deployment operations might require additional memory and processor capacity on the PowerVC management host. It is recommended that you increase the recommended memory by 100 MB for each concurrent operation over 10 that you plan to run. For example, add 4 GB if you plan to run 50 concurrent operations. If you are using only SAN storage and you plan to batch deploy over 100 virtual machines that are based on one image, you must make multiple copies of that image and deploy the virtual machines in batches of 10. The following settings might increase the throughput and decrease the duration of deployments: Use the striping policy instead of the packing policy. Limit the number of concurrent deployments to match the number of hosts.
Maximum number of concurrent migrations	You cannot exceed the maximum number of concurrent migrations designated for the source and destination hosts. The maximum number of concurrent migrations depends on the number of migrations supported by the Virtual I/O Servers that are associated with each host.
Maximum number of concurrent operations supported for import and export of images	PowerVC supports 4 concurrent image export or import operations. While performing image import or export operations, make sure the following conditions are met: PowerVC management server must have Fibre Channel connectivity with the storage provider registered. Hardware configuration on the PowerVC management server: 4 CPU, 16 GB Memory, and swap 5 GB. Ensure that sufficient space is available to copy all volumes. Exporting an image requires double the size of the volumes. For example to export a 2 TB image, the space required is more than 4TB. Image export and import are long duration operations. The duration depends on the size of image volumes and load on the PowerVC management server.
Size of the Virtual I/O Server partition	Use the Virtual I/O Server Performance Advisor tool to ensure that the Virtual I/O Server partition is properly sized.
Maximum number of displayed images	The PowerVC user interface displays a maximum of 400 images. So, if you have more than 400 images, you can work with only a subset of them on the PowerVC user interface.
Number of concurrent virtual machine deletion operations	When you delete virtual machines on multiple hosts, run the operations concurrently across the hosts. It is recommended that you do not exceed 50 concurrent delete operations.
Maximum number of storage volumes	For optimal performance, it is recommended that you use PowerVC to manage at most 10,000 storage volumes, with at most 128 volumes per virtual machine. When using an IPG in a storage connectivity group, the number of volumes attached to a virtual machine can scale more than 128 volume attachments. Refer to this topic for information on limits and restrictions for supported storage providers: Planning for storage providers. To overcome limits for a storage provider, use multiple storage providers. Note: For NovaLink, you can deploy an image that has at most 25 volumes. Additionally, you can capture at most 25 volumes when you capture a virtual machine. A single instance of an IBM XIV® storage system can attach up to 511 volumes per host mapping.
Networking name resolution	For Virtual I/O Server instances that do not have IPv6 configured, avoid overhead by configuring them to return only IPv4 addresses. To do this, specify the following line in the Virtual I/O Server /etc/netsvc.conf file: `hosts=local4,bind4` .