Chapter 11. Working With Virtual Machines
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with previous versions will not have the dynamic scaling capability unless you update them using the
following procedure.
11.11.2. Updating Existing VMs
If you are upgrading from a previous version of CloudPlatform, and you want your existing VMs
created with previous versions to have the dynamic scaling capability, update the VMs using the
following steps:
1. Make sure the zone-level setting enable.dynamic.scale.vm is set to true. In the left navigation bar
of the CloudPlatform UI, click Infrastructure, then click Zones, click the zone you want, and click
the Settings tab.
2. Install Xen tools (for XenServer hosts) or VMware Tools (for VMware hosts) on each VM if they
are not already installed.
3. Stop the VM.
4. Click the Edit button.
5. Click the Dynamically Scalable checkbox.
6. Click Apply.
7. Restart the VM.
11.11.3. Configuring Dynamic CPU and RAM Scaling
To configure this feature, use the following new global configuration variables:
• enable.dynamic.scale.vm: Set to True to enable the feature. By default, the feature is turned off.
• scale.retry: How many times to attempt the scaling operation. Default = 2.
11.11.4. How to Dynamically Scale CPU and RAM
To modify the CPU and/or RAM capacity of a virtual machine, you need to change the compute
offering of the VM to a new compute offering that has the desired CPU and RAM values. You can
use the same steps described above in Section 11.11, “Changing the Service Offering for a VM”, but
skip the step where you stop the virtual machine. Of course, you might have to create a new compute
offering first.
When you submit a dynamic scaling request, the resources will be scaled up on the current host if
possible. If the host does not have enough resources, the VM will be live migrated to another host in
the same cluster. If there is no host in the cluster that can fulfill the requested level of CPU and RAM,
the scaling operation will fail. The VM will continue to run as it was before.
11.11.5. Limitations
• You can not do dynamic scaling for system VMs on XenServer.
• CloudPlatform will not check to be sure that the new CPU and RAM levels are compatible with the
OS running on the VM.
2 http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1012764