Mountpoints are fun and easily can solve issues with more than 26 drive letters (don't ask), but recently we ran into several issues with monitoring the mountpoints.  In particular we have a report that is based on past growth history of a database, disk size and disk free space, and it estimates when a drive will be at 80% capacity and when it will fill up.   With 100's of database servers this report can prioritize and pro-actively identify which server will encounter a problem next and when.  Of course the limitation is in bold, drive. 

Report Example:

When we began using Mountpoints the report was not as accurate and it needed to be adjusted.  We have some internal services that collect the drive size and free space to a central DBA database.  Review of this monitoring reveals it is using a WMI Query, a quick review of the WMI SDK shows another call that will pick up mountpoints, Select * from WIN32_Volume.  Life is good.

Not so quick after hurdling from drives to drives and mountpoints, a problem was revealed where the WMI call failed on two servers.  Englightenment.  These two sql servers have also been giving us odd issues with SQL Management Studio (SSMS), which is highly dependent on WMI, SMO, .NET and probably some other stuff.  Fixing WMI on these two servers fixed the issue and corrected the SSMS issues.

Steps to fix WMI (Thanks to our Windows Team for the steps below):

Here is a short quick Visual Basic Script (VBS) you can save to a text file with a .VBS Extension to see the call to WMI to check disk space for mount points or drives.  It filters out certain mount points for Polyserve as we don't want to monitor those, also for some reason z:\ is mapped in our environment and this wmi script pulls that with nulls, so you need to test for those.  You can also use Powershell, but it is using a wmi call underneath the hood as well, and we have yet to install powershell on all our servers.

Set DiskSet = GetObject("winmgmts:{impersonationLevel=impersonate}!//BCCMAPP02")_
    .ExecQuery("Select * from Win32_Volume")
For Each objItem In DiskSet
    Ignore = False
    if len(objitem.name) >= 51 then
        If UCase(Left(objitem.name,51)) = _
            UCase("C:\Program Files\PolyServe\MatrixServer\conf\mounts") Then
            Ignore = True
        End If
    End If

    If Ignore = False Then
        msgbox(objItem.Name & vbCrLf & "Percent Free = " & _
            round((objItem.freespace/objItem.Capacity)*100,2) & _
            " = " & objItem.freeSpace & " = " & objItem.Capacity)
    End If

Next