Map a network drive to be used by a service
Suppose some Windows service uses code that wants mapped network drives and no UNC paths. How can I make the drive mapping available to the service's session when the service is started? Logging in as the service user and creating a persistent mapping will not establish the mapping in the context of the actual service.
Use this at your own risk. (I have tested it on XP and Server 2008 x64 R2)
For this hack you will need SysinternalsSuite by Mark Russinovich:
Step one: Open an elevated cmd.exe prompt (Run as administrator)
Step two:
Elevate again to root using PSExec.exe:
Navigate to the folder containing SysinternalsSuite and execute the following command
psexec -i -s cmd.exe
you are now inside of a prompt that is nt authority\system and you can prove this by typing whoami. The -i is needed because drive mappings need to interact with the user
Step Three:
Create the persistent mapped drive as the SYSTEM account with the following command
net use z: \\servername\sharedfolder /persistent:yes
It's that easy!
WARNING: You can only remove this mapping the same way you created it, from the SYSTEM account. If you need to remove it, follow steps 1 and 2 but change the command on step 3 to net use z: /delete.
NOTE: The newly created mapped drive will now appear for ALL users of this system but they will see it displayed as "Disconnected Network Drive (Z:)". Do not let the name fool you. It may claim to be disconnected but it will work for everyone. That's how you can tell this hack is not supported by M$.
I found a solution that is similar to the one with psexec but works without additional tools and survives a reboot.
Just add a sheduled task, insert "system" in the "run as" field and point the task to a batch file with the simple command
net use z: \servername\sharedfolder /persistent:yes
Then select "run at system startup" (or similar, I do not have an English version) and you are done.
You'll either need to modify the service, or wrap it inside a helper process: apart from session/drive access issues, persistent drive mappings are only restored on an interactive logon, which services typically don't perform.
The helper process approach can be pretty simple: just create a new service that maps the drive and starts the 'real' service. The only things that are not entirely trivial about this are:
The helper service will need to pass on all appropriate SCM commands (start/stop, etc.) to the real service. If the real service accepts custom SCM commands, remember to pass those on as well (I don't expect a service that considers UNC paths exotic to use such commands, though...)
Things may get a bit tricky credential-wise. If the real service runs under a normal user account, you can run the helper service under that account as well, and all should be OK as long as the account has appropriate access to the network share. If the real service will only work when run as LOCALSYSTEM or somesuch, things get more interesting, as it either won't be able to 'see' the network drive at all, or require some credential juggling to get things to work.
A better way would be to use a symbolic link using mklink.exe. You can just create a link in the file system that any app can use. See http://en.wikipedia.org/wiki/NTFS_symbolic_link.