Considerations for deploying captured or imported images

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Review these considerations before deploying images.

Placement considerations
  • If you are deploying virtual machines that will be part of a collocation rule, you should deploy them to the hosts that you want the virtual machines on. After deployment, you can add them to a new or existing collocation rule. Otherwise, if you want to add the virtual machines to a collocation rule, you might have to migrate them to a specific host first.
  • Some IBM® Power® servers are only capable of running Linux® workloads. When deploying an AIX® or IBM i image, such hosts are not considered for placement.
  • 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.
Naming considerations
  • When the virtual machine name is specified, it is used as the host name for the virtual machine as well. However, you can change the host name manually in the virtual machine. If the virtual machine name includes characters that are not allowed in host names, such as periods, the host name becomes incorrect or might not be the expected value.
  • (Linux or AIX only) To set the host name to be the DNS value, you must enable the cloud-init set_hostname_from_dns module. For instructions, see Installing and configuring cloud-init.

  • When you set a default domain name for newly deployed virtual machines in PowerVC, that domain name is always used. If you do not set a default domain name, the default is automatically set to the domain name of the PowerVC management server. If PowerVC cannot retrieve that value and you do not set a default domain name, the default is automatically set to 'localdomain'. You can then set the domain name manually after you deploy an image. See the documentation for the operating system on the deployed virtual machine for information about how to manually set the domain name.

  • When deploying a single virtual machine from an image, it is recommended that the length of the virtual machine name plus the domain name is fewer than 64 characters. If you do not follow this recommendation, the virtual machine's long host name can become too long. Long host names can cause problems with virtual machine activation and system services.
  • When deploying multiple virtual machines from an image, it is recommended that the length of the virtual machine name plus the domain name is fewer than 25 characters. If you do not follow this recommendation, the virtual machine's long host name can become too long. Long host names can cause problems with virtual machine activation and system services.
Storage considerations
  • If you deploy a multi-volume image that has one or more data volumes, and the resulting virtual machine is later deleted, the virtual machine's data volumes that were cloned from the image's data volumes will also be deleted.
  • PowerVC can capture and deploy AIX 6.1 or 7.x virtual machines with EMC PowerPath enabled for the boot disks. PowerPath driver version 5.7 SP2 is required.
  • For AIX 7.1 virtual machines that use EMC PowerPath, deploys must use compute templates that specify at least 2 GB of memory.
  • When deploying a thick image backed by a shared storage pool, the Virtual I/O Server makes a full copy of the image. The location of the copy depends on the workload on the Virtual I/O Server and how your environment is set up. The time it takes to make this full copy depends on the speed of the backing Fibre Channel device, the speed of the Fibre Channel network, the resources allocated to the Virtual I/O Server and the current workload on the Virtual I/O Server. This copy operation has lower priority on the Virtual I/O Server than I/O requests. Therefore the copy operation could take up to one or more minutes per GB to complete on a heavily loaded and undersized Virtual I/O Server.
Limitations
  • PowerVC supports a maximum of 50 concurrent deployments. It is recommended that you do not exceed 8 concurrent deploys per host.
  • If 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 storage connectivity group that you select determines which hosts are available as target hosts in the deployment operation. For more information, see the Storage connectivity groups topic.
  • The number of concurrent deploys should not be greater than the number of image volumes. For example, if eight deployments are expected to run in parallel, then it is recommended that you have eight different source image volumes to clone from. This is to help avoid timeouts in some environments, and is not a requirement.
Other considerations
  • You can upload configuration scripts or add configuration data at the time of deploying a virtual machine using the activation input option. This script or data will automatically configure your virtual machine according to your requirements, after it is deployed. For more information about the accepted data formats in cloud-init and examples of commonly used cloud configuration data formats, see the cloud-init documentation.
    Note: The file or scripts you upload and add here are used by the cloud-init initialization package for AIX virtual machines only. For any other operating system, the activation engine does not use the data you upload for activation.
  • PowerVC supports deployment of user-specified OVF image formats. The user-specified OVF can contain ProductSections for other software beyond the basic system and network configuration that is provided by the PowerVC default OVF. The ProductSections section might need user input during deployment. The values for the ProductSections keys can be set in the Server metadata key-value pairs section of the Activation Input.
    Note: Run the powervc-volume-image-import command to import a user-specified OVF that is associated with the image.
  • The HMC automatically removes the virtual optical drive, but in a NovaLink environment, the activation virtual optical drive resides on the system until the virtual machine is migrated, remote restarted, or deleted. If you want to manually delete it, you can use the NovaLink pvmctl command. For details, see PowerVM® NovaLink command-line interface.
  • On AIX, when using a version of cloud-init that PowerVC does not support, set ghostdev to 0 on every virtual machine. Instead of making this change manually, you can add these lines in the Activation Input box during a deploy: 
    #cloud-config    
runcmd:     
- chdev -l sys0 -a ghostdev=0