Hi, this is Matt, from Zerto. The maximum size of an individual VMDK that Zerto can protect is dependent on what Hypervisor you are using. Please see page 13 of the below linked Zerto Scale and Benchmarking Guide for a table of such limits Zerto has. Per the documentation, 16TB would be supported for VMware and Hyper-V, but is not supported for Azure, and is the upper limit for AWS.