If you are planning on using Buffer Pool Extension (BPE) in SQL Server 2014 or SQL Server 2016 you need to think about where you want to put the BPE file on the SSD, especially as it relates to the Windows OS Security on the file system. The most important think to remember when placing the BPE file on the hard drive is that you want to place it into a folder, not directly into the root of the drive. The reason for this is that the Windows OS has User Access Controls (UAC) enabled which will prevent the SQL Server from writing to the root of the drive. Even if you have UAC disabled today (which I don’t recommend) if it gets enabled in the future this could cause problems with access to the BPE file. It is much easier to simply put the file into a folder and not have to worry about UAC biting you.