Once a linked clone desktop pool has been created, you have a few additional options or controls to manage them back on the main management webpage – VMware uses the terms Refresh, Recompose and Rebalance to describe the three main tasks that may need to be carried out on your linked clones. VMware uses quite neutral-sounding terms for these tasks – the words “refresh”, “recompose” and “rebalance” sound quite reassuring and non-intrusive. Don’t be fooled by the soft-sounding words, these changes have a huge impact on users and can take some time to complete, depending on the number of virtual desktops in the pool.
Refresh – This option resets the delta disks back to the original state. If you are familiar with VMware Snapshots, the process is analogous to reverting the VM back to its original state when it was first created. Any modifications the user has made to the virtual desktop will be discarded. Remember, this option can also be triggered by the logoff event (using the Pool Settings page), so every time the user logs off, the delta disk is discarded and regenerated. A refresh can be quite an intrusive task because if affected users are currently logged in, they will receive a message forcing them to log out of their environment. The virtual desktops are all powered off and new delta virtual disks are created.
Recompose – In this process, the linked clones are attached to a new replica. The net effect is that all the changes accrued in the delta disk are lost, and users get a brand new virtual desktop. The Recompose command can be used to roll out new software or a new service pack – effectively replacing the virtual desktop with a new build without having to re-create the virtual desktop pool and entitle it for the correct users. A recompose is a very intrusive task - if affected users are currently logged in, they will receive a message forcing them to log out of their environment. The next time they log in they may be receiving a very different desktop look and feel.
Rebalance – This option is there if you have selected different storage locations for your virtual desktops. It could be the case that you have more virtual desktops in one datastore than another. The Rebalance command attempts to redistribute the VMs evenly among the datastores. It’s essentially a storage management option.
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