User Profile Disks (UPD) is a new technique introduced in Windows Server 2012 to deal with profiles on VDI deployments for Session-Based deployments as well as Virtual Machine-Based deployments. For more information on setting up UPD also see this TechNet Wiki:
If you have read through the wiki or have already been working with UPD you'll now that the files share that contains the UPD files (.vhdx files) are made up of the users Active Directory SID. To make it easier to identify what UPD file belong to what user, I created a simple PowerShell script that could help out.
Run the script from a PowerShell prompt and specify the parameter where the UPD files are stored.
The output will look something like below and a export.csv file is also created containing the results.
You can find the file on Microsoft TechNet Gallery: