Putting SQL Server data files in a different partition I have a SQL Server and I put the data files (the .mdf) on a different partition. 

Windows runs from C: and the data files and logs are on D: 

Is it advantageous or disadvantageous to separate the data files on different partitions? 

There is only one disk and it has been partitioned to C: and D: My main focus is SQL Server performance all around like reading and writing.
It won't matter for performance but it could matter for other reasons.

To get better performance, you need to have it split across different physical hardware; splitting files across logical partitions does not help or hurt performance. But I wouldn't worry about this unless you start seeing disk activity as a bottleneck.

There are benefits from this approach:


You can back up the D: drive without having to do a system image backup.
You can restore the D: drive without restoring the entire system. 
If you get to a point where you need more space, it is easier to move the D: drive to another physical disk than to have to move the C: drive or relocate the database files.