I am aware that SQL Server instances need write access not for my user account (which is in fact irrelevant to that service's context) but for the user account or security principal under which the SQL Server Service is running. (In my case NT Service\MSSQLSERVER)
Having done that, and having verified that when I create a new database in this folder, I can write to this folder, and that the database files created by this server instance are created with the user MSSQLSERVER, nevertheless, I still lack the ability to write to any folder on drive E, from the context of MS SQL, unless I also add "write" permissions for "Everyone", adding write access to the "MSSQLSERVER" is not enough.
There must be some other level of NTFS security involved here. It almost reminds me of a domain trust issue. This is on MS SQL Server 2012, running on Windows 8 Pro.
What do you do next, if adding the MSSQL account name found in the "Log On" tab of the service, does not work? It's frustrating, but I'm stuck with giving "Everyone" write access to this folder on drive E before any folder is writeable by SQL Server. Drive E in my case is a regular local hard drive, not a network folder. (I'm not dumb enough to try to run SQL on a network mounted drive.)