Upgrading Flash Accel Guest OS Agents
The Flash Accel Guest OS Agent upgrade is a so-called "synthetic upgrade." It combines uninstallation of the current agent version with installation of the new agent version. Like a true upgrade, a synthetic upgrade preserves the cache allocation for the VM and other key caching configuration information. Unlike a true upgrade, it destroys the cache, which is cold on VM restart.
Before you begin 
You must disable caching on the VM before upgrading the Guest OS Agent. The VM must be powered on.
An account with administrator privileges is required.
You must disable Windows User Access Control (UAC) if you plan to log in to the virtual machine with credentials other than those of the built-in Administrator account. The account you use must be in the Administrators group, and it cannot be in the Users group.
It is a good idea to take a snapshot of your VMs before you upgrade the software, in case you need to revert to an earlier version.
Note: The virtual machine is shut down or restarted when the upgrade completes. You need to be sure this is an acceptable time to take the virtual machine offline.
Steps 
1.
From the VM Inventory page of the FAMC, click the wrench icon for the VM on which you want to upgrade Flash Accel software and select Software > Upgrade.
From the VM Inventory page of the FAMC, select each VM on which you want to upgrade Flash Accel software and click VM Agent Upgrade in the Bulk Actions area of the FAMC.
The virtual machine upgrade dialog box opens.
2.
Click Upgrade.
Note: Select the Reboot check box if you want to restart VMs automatically after upgrade.
Result 
The Flash Accel Guest OS Agent is upgraded on the VM. If you selected the Reboot check box, the VM is restarted. Otherwise, it is shut down.
Note: Flash Accel sets the disk.enableUUID flag to TRUE on the VM if necessary.
After you finish 
Shut down or migrate the VM before upgrading the Flash Accel Host Agent. ESXi hosts must be in maintenance mode before you can upgrade Host Agents.
Parent Topic: Upgrading Flash Accel components