When a user logs on, regardless of whether they have a local, roaming, mandatory (or even no) profile, they will have a folder created in the location specified under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\ProfilesDirectory – by default this is %SystemDrive%\Users.

For the majority of cases this will be C:\Users, and there are a couple of things to note about changing this:

1. It is not supported to change this by editing the registry after installing Windows – the supported method is to set the <ProfilesDirectory> property in the unattended setup XML file

2. If this is changed to point to a different volume, then the VirtualStore (registry and file virtualization) will not work

So basically, don’t do it :)
(See KB949977)

 

If space on the system volume is a problem, there are other possible options available:

1. On a per-user, per-library basis, set the Location property to point to a different path

2. Use folder redirection via group policy

3. Move the page file to another volume (to be able to get memory dumps, you can use DedicatedDumpFile)

Do not go deleting anything under WinSxs to reclaim space either - while you might think you do not need it, there is no way of knowing if the system might later…

 

If your environment is a Terminal Server or Remote Desktop Services Session Host, then the space used by profiles can become quite large indeed (a good reason to use mandatory profiles or folder redirection) – there are a couple of group policy settings which can help alleviate the problem:

1. “Delete cached copies of roaming profiles” (See KB274152)

2. “Delete user profiles older than a specified number of days on system restart” (See KB940017)