VMware VMDK Size Limitations
VMware imposes the following limits that affect Zerto Virtual Replication:
■ ESXi 5.5 and higher hosts: A protected VMDK cannot be more than 32TB.
The sum of all VMDKs of all virtual machines protected on a particular ESXi must be lower than 40TB. Using an ESX tweak, this can be extended to 64TB.
■ ESXi 5.0 and 5.1 hosts: The sum of all VMDKs of all virtual machines protected on a particular ESXi must be lower than, by default, 20TB. Using an ESX tweak, this can be extended to 64TB.
■ ESX/ESXi 4.x hosts: The sum of all VMDKs of all virtual machines protected on a particular ESXi must be lower than, by default, 4TB. Using an ESX tweak, this can be extended to 32TB.
These limits include all virtual machines running on that host as well as the VRA and any shadow VRAs.
Use the following procedure to adjust the VMDK size limitation.
Note: The net effect of adjusting the VMDK size limitation is that the ESX/ESXi kernel will require a small amount of additional memory, such as the 128MB used to get a maximum of 32TB for ESX/ESXi 4.x hosts specified in the procedure, for the larger heap, but it will allow virtual machines with more than 4TB (ESXi/ESX 4.x) or 8TB (ESXi 5.0/5.1) of virtual disk to be addressed.
To adjust the VMDK size limitation:
1. Log in to vCenter Server or the ESX/ESXi host using VMware Infrastructure (VI) Client. If connecting to vCenter Server, select the ESX/ESXi host from the inventory.
2. Click the Configuration tab.
3. Click Advanced Settings.
4. Select VMFS3.
5. Update the field in VMFS3.MaxHeapSizeMB.
■ In ESX/ESXi 4.x, the maximum heap size is 128MB.
■ In ESXi 5.x, the maximum heap size is 256MB.
6. Reboot the host for the changes to take effect.