Why does computer name change create new Users\<name> folders?

On Thu, 15 Feb 2007 07:15:56 -0800, DanielLipkie

>When I first received my new pc w/ Vista Home Premium I created a std account
>Daniel. I noticed that from the Admin account I could navigate to the Users
>folder and see a folder "Daniel".
>
>Later I changed the name of my pc to "E1505_D" and I then see another folder
>Users\Daniel.E1505_D. So I now have Users\Daniel and Users\Daniel.E1505_D.
>
>Could someone provide a pointer to documentation on this feature of Vista?

I've seen similar ugliness in XP, and it is prolly deeply rooted in
the way user accounts work in NT.

Each user account has a unique identifier that is the "real" name of
the account. When the account is created, the name you give the
account is used as the base name for the account's subtree (which in
XP is within C:\Document & Settings, in Vista it's in C:\Users).

If you rename the account, things get murky; at some levels, the
original name persists and the new name is "grafted on". For example,
the account subtree retains the same name when seen as a raw file
system, though the namespace account name may change to the new one.

By the same token, trying to re-create the same account name spawns a
new "real" identier, so the old and new identities are not fused, and
a new user subtree with mangled name is created next the old one. The
mangling of the name is needed to avoid a same-name collision with the
existing account subtree, which remains bound to the original "real"
account identifier, while the new subtree belongs to the new one.

This can create all sorts of problems, as sometimes the old name is
still referenced. It's an ugly consequence of separating the names
you use from the real identifiers, which is in turn required if the
same account is to work under a new (changed) name.


Two contexts tend to precipitate problems like this.


In XP, one can do a "repair install" of Windows, which is sometimes
needed as a way of fixing certain problems, such as an invalidated HAL
after a motherboard change. Unfortunately, it's often resorted to as
a general fix for situations that don't benefit from it.

When you do a "repair install" in XP, you are prompted to create a new
user account. If you attempt to re-use your existing account by
entering the same name, then a new account is created with the same
name, though behind the scenes it will have a different "real"
identifier. To avoid a name collision, the user subtree will have a
mangled form of the name, and when you boot up, the Welcome screen
will show both identically0named accounts.

If you log into the wrong one, you don't see your data. If you delete
the wrong one, and Yes to delete the data associated with it, then you
lose all your data. If NTFS, your chances of data recovery are small.


In Vista, a similar situation arises when one uses the Sysprep tool
during a master system build, just before harvesting the installation
via ImageX (the same may happen in XP but I haven't tried Sysprep etc.
there). Both the Sysprep'd master PC, and any new PC built from the
installation image, will then start off with the existing user
account(s) still present, but will prompt to create new accounts when
first run. Unlike in XP, you cannot "Next" past this step :-(

Also unlike XP, you can't enter the name of an existing account, so
you don't have the same problem with two accounts that appear
identical, one with your data and one without.

But the name of the new account that Vista forces you to create, will
also become the registered user name; something to rermember to clean
up via Regedit if you use something like "Useless Crap" as the account
name with the intention of deleting the account later ;-)

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Saws are too hard to use.
Be easier to use!

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