Information Technology Reference
In-Depth Information
Perform the following steps to migrate a VM to a different host and datastore using the com-
bined vMotion and Storage vMotion:
1.
Launch the Web Client if it is not already running.
2.
Navigate to the Hosts And Clusters or VMs And Templates view.
3.
Right-click the VM whose virtual disks you want to migrate from the inventory tree on
the left, and then select Migrate. The same dialog box is used to initiate a vMotion and a
Storage vMotion operation opens.
4.
Select Change Both Host And Datastore and click Next.
This option will be grayed out if your cluster hosts are vSphere 5.0 or earlier.
5.
Select the destination resource and click Next.
6.
Pick the host that you wish to migrate the VM to and click Next.
7.
Select a destination datastore or datastore cluster.
8.
Select the desired virtual disk format (Same Format As Source, Thick Provision Lazy
Zeroed, Thick Provision Eager Zeroed, or Thin Provision). Click Next to continue.
9.
Change the vMotion priority if desired, and click Next to review the changes.
10.
Finally, review the changes about to be made and click Finish.
When you're combining vMotion and Storage vMotion, the storage is the i rst migration to
take place; the reason behind this is twofold. First, hard disks are both larger and slower than
memory; therefore the Storage vMotion will take signii cantly longer than the vMotion. Second,
the rate of change to disk-based storage is usually less than that for memory. If the vMotion
operation happened i rst, the memory bitmap i le (discussed earlier in this chapter) would grow
much larger while waiting for the Storage vMotion task to complete. That's why it makes a lot
more sense for the Storage vMotion operation to happen i rst.
Like vMotion, Storage vMotion (or a combination of both) is a great approach for manually
adjusting the load or utilization of resources, but they are ultimately
reactive
tools. vSphere DRS
and Storage DRS leverage vMotion and Storage vMotion to bring a level of automation to help
balance utilization across clusters.
Exploring vSphere Distributed Resource Scheduler
When we introduced you to vMotion and Storage vMotion, we stated that they were a way of
manually balancing loads across VMware ESXi hosts. vSphere Distributed Resource Scheduler
(DRS) builds on this idea by making the load balancing
automatic
. The groups are clusters,
which we introduced in Chapter 3, “Installing and Coni guring vCenter Server,” and discussed
again in Chapter 7.
vSphere DRS is a feature of vCenter Server and has the following two main functions:
To decide which node of a cluster should run a VM when it's powered on, or
intelligent
placement
◆
◆
To evaluate the load on the cluster over time and either make recommendations for
migrations or use vMotion to automatically move VMs to create a more balanced cluster
workload
