Just recently updated all of my hosts from ESXi 5.0 U2 to ESXi 5.1 U1. Noted the following in the release notes:
ESXi 5.1 Update 1 Release Notes
Enabling or Disabling View Storage Accelerator might cause ESXi hosts to lose connectivity to vCenter Server
If VMware View is deployed with vSphere 5.1, and a View administrator enables or disables View Storage Accelerator in a desktop pool, ESXi 5.1 hosts might lose connectivity to vCenter Server 5.1.
The View Storage Accelerator feature is also called Content Based Read Caching. In the View 5.1 View Administrator console, the feature is called Host caching.
Workaround: Do not enable or disable View Storage Accelerator in View environments deployed with vSphere 5.1.
I was planning on enabling View Storage Accelerator on some of my larger use pools during one of my next maintenance windows during a recompose when I also planned to push out the new tools. I thought this was already resolved in a 5.1 patch last year:
Is this still really an issue? I'd think this would be something that would be fixed by now, considering how this feature is trumpeted by VMware.