The purpose of this post is to highlight the key areas for monitoring vSAN performance. There are some truly insightful tools built into vCenter that can monitor performance from the application all the way down to the individual storage disk. Read on to learn more.

vSAN Thin vs Thick Provisioning. Let’s start with how vSAN defines a thin or thick provisioned disk. Within a vSAN Storage Policy there is a setting called ‘Object Space Reservation’ (OSR). When the OSR value is equal to 0, it is considered a thin disk and when it is set to 100, it is considered a thick disk. A vSphere cluster backed by a vSAN datastore can have multiple vSAN Storage Policies and different VMs within a cluster can be assigned both a thin or thick provisioned storage policy – it is not an either/or situation. It is also valid to assign a percentage of 1 to 99 for the OSR value, I'm at a loss why that would be necessary.