From 535e74d86e66a7304eaa4ad4fe2ce19be60e493c Mon Sep 17 00:00:00 2001 From: Jessica Date: Thu, 8 Aug 2013 17:58:12 -0700 Subject: [PATCH] CLOUDSTACK-867. DOC. Document dynamic CPU and RAM scaling for running VMs. --- .../changing-service-offering-for-vm.xml | 47 ++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-) diff --git a/docs/en-US/changing-service-offering-for-vm.xml b/docs/en-US/changing-service-offering-for-vm.xml index 4fc9ef4270b..22724eb9ede 100644 --- a/docs/en-US/changing-service-offering-for-vm.xml +++ b/docs/en-US/changing-service-offering-for-vm.xml @@ -28,7 +28,8 @@ Log in to the &PRODUCT; UI as a user or admin. In the left navigation, click Instances. Choose the VM that you want to work with. - Click the Stop button to stop the VM. + (Skip this step if you have enabled dynamic VM scaling; see .) + Click the Stop button to stop the VM. @@ -50,5 +51,49 @@ Select the offering you want to apply to the selected VM. Click OK. +
+ + CPU and Memory Scaling for Running VMs + (Supported on VMware and XenServer) + It is not always possible to accurately predict the CPU and RAM requirements + when you first deploy a VM. + You might need to increase or decrease these resources at any time during the life of a VM. + You can dynamically modify CPU and RAM levels to + change these resources for a running VM without incurring any downtime. + Dynamic CPU and RAM scaling can be used in the following cases: + + New VMs that are created + after the installation of &PRODUCT; 4.2. + If you are upgrading from a previous version of &PRODUCT;, + your existing VMs created with previous versions + will not have the dynamic scaling capability. + + User VMs on hosts running VMware and XenServer. + System VMs on VMware. + VM Tools or XenServer Tools must be installed on the virtual machine. + The new requested CPU and RAM values must be within the constraints allowed by the hypervisor + and the VM operating system. + + 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. + + 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 , 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. + &PRODUCT; will not check to be sure that the new CPU and RAM levels are compatible + with the OS running on the VM.
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