Hey Tim,
I had the same issue, and found this forum:
http://www.neowin.net/forum/topic/1264602-windows-10-disable-the-low-disk-space-warning/
It seems to have worked for me.
A lot of people don't understand that some of us just have many extra storage drives that are exactly just that; storage. First they tell you to delete your files so that Windows can utilize the space. Windows isn't touching this drive unless I tell it to write to it.
In my scenario I have a separate HDD that Windows 10 writes a backup file to every week. It's set to write until full capacity then delete older backups, so guess what? IT'S ALWAYS FULL!
The notifications were a pain in the ass, but I haven't seen one in 24 hours (knocks on wood).
Thanks PhilxBefore, seems to have solved the issues, now.
Had problems doing what the thread above suggested but after a few G-Searches managed to pin it down. For others with this problem the final instructions are:-
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assuming that you have never run the 'hidden' Administrator account since upgrading to Win10.
Tap Windows Key and type "cmd"
right click on the "Command Prompt" in the menu and select "Run as Administrator".
You should now be in a DOS box.
Enter the command
which should list
all available users on the system, one of which is the Administrator account.
Then type
net user Administrator /ACTIVE:YES
and then password protect this using
net user Administrator *
and entering and re-entering a password at the prompts.
This account should now be password protected. Obviously try to make this password as secure as possible as this account is the main Administrator account for the computer and has
ALL privileges and will now appear on the logon screen list of users. If you think it is necessary it is possible to hide this account when you are finished by re-entering the DOS box and typing:-
net user Administrator /ACTIVE:NO
but do remember the password in case you need to go back into the hive!
Now log-off the system and log back on with the Administrator account. If for any reason the account does not appear on the list of users at log-on re-do the above instructions and ensure that you have not misspelled or used the wrong case in the above commands and have another go. It may be necessary to reboot the system prior to continuing, I did for safety's sake and found that I had used the "=" sign rather than the colon and the Administrator did not appear.
Now run regedit (Windows key, type "
regedit", right-click, select
run as administrator) as for Command prompt.
Within regedit find
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows Search\Gather (HKLM\....\Gather).
Right click on
Gather, select
permissions, click on
Advanced Button, click on
Change.
Top line in the dialog-box should read
Owner: TrustedInstaller.
In the dialog-box below enter "
Administrator", note that this is case sensitive and should be the same as the username in the CMD box at the beginning of the instructions, now press
OK and
ADD.
On first line (Principal

click on "
Select a principal", enter "
Administrator" in the text box then press
OK and click on checkbox "
Full Control" then
OK.
Hit
Apply then
OK, highlight
Administrator in "
Group or Username" table and it should show full access for
HKLU Key "Gatherer", then click
OK.
Having set the permissions for the user
Administrator double click on key
LowDiskMinimumMBytes and set the value to
hex 0 pressing "
Enter" afterwards.
This should stop the messages about running out of space on any drive that is not the system disc. It seems to have worked for me, so far, with an E: drive that was 100% full and only 15Gb in size that was a Fujitsu portable backup drive that theoretically would allow me to rebuild a hard drive to original specs. Whilst I have kept this drive I have, so far, never needed to use it and I probably could get rid of it, however, I haven't.
It may be necessary to do the same as above with "
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows Search\Gathering Manager" which is the next key to
HKLM\...\Gather modifying
BackOffLowDiskThresholdMB to
hex 0 but as mentioned I have not seen a message, so far.
Having changed the key(s) it is necessary to change the ownership of the 2 keys "
Gather" (and "
Gathering Manager") back to
TrustedInstaller.
To do this:-
Whilst still in
Regedit right-click "
Gather", click on
Advanced button, click "
change" and in the box type "
NT SERVICE\TrustedInstaller" and hit
OK. NB there IS a space between the
NT and the
SERVICE. You should see ownership change back to
TrustedInstaller, then
OK in
Advanced Settings dialog box. At the same time make sure that only
TrustedInstaller has access to full privileges for all keys that have been changed.
You will need to restart to ensure the new settings are retained.
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I think that about wraps up the solution to the problem I was having. Thanks to PhilxBefore who put me on the right track (refer link in his post) and the authors of this post, DeusProto and GrandMaster (who had the same problem I did at about the same time) together with tenforums.com and askvg.com who solved the problems of finding the Administration account and reinstating the TrustedInstaller ownership, respectively.
Hopefully this is now officially solved.
Tim Barker.