>I am working on a new installation. The company DBA sent me email with directions where to install (attach) my database. It looks like she created two folders, one for mdf and another for .ldf. Her email says "Make sure to use default file directory for DB install (E:\AppName\data and E:\AppName\log"
>
>Do I understand correctly that she wants the mdf and ldf to be placed in two different directories? Why would they use this approach?
>
>TIA

Found this recent article that confirms it's still being considered a best practice

http://sqlmag.com/storage/sql-server-storage-best-practices

See also

https://msdn.microsoft.com/en-us/library/bb402876.aspx

and this nice presentation by Jes Borland

http://www.brentozar.com/archive/2012/09/how-sql-server-works-log-file-video/