If you instruct the New Virtual Machine wizard to create a new virtual disk during a custom configuration, the wizard prompts you to set the size of the virtual disk and specify whether to split the disk into multiple virtual disk (.vmdk) files.
A virtual disk is made up of one or more virtual disk files. Virtual disk files store the contents of the virtual machine hard disk drive. Almost all of the file content is virtual machine data. A small portion of the file is allotted to virtual machine overhead. If the virtual machine is connected directly to a physical disk, the virtual disk file stores information about the partitions that the virtual machine is allowed to access.
You can set a size between 0.001 GB and 8 TB for a virtual disk file. You can also select whether to store a virtual disk as a single file or split it into multiple files.
Select Split virtual disk into multiple files if the virtual disk is stored on a file system that has a file size limitation. When you split a virtual disk less than 950 GB, a series of 2-GB virtual disk files are created. When you split a virtual disk greater than 950 GB, two virtual disk files are created. The maximum size of the first virtual disk file is 1.9 TB and the second virtual disk file stores the rest of the data.
For custom configurations, you can select Allocate all disk space now to allocate all disk space immediately rather than allow the disk space to gradually grow to the maximum amount. Allocating all the disk space immediately might provide better performance, but it is a time-consuming operation that requires as much physical disk space as you specify for the virtual disk. If you allocate all the disk space immediately, you cannot use the shrink disk feature.
After you create a virtual machine, you can edit virtual disk settings and add additional virtual disks.