c# More File Reads Vs. More File Open/Close speed
<p>I have an application which accesses a flat file filesystem whose structure I have to decide. My filesystem stores data for users for each day of the year for every year and each day's data has information of the form <code>HH:mm, value</code>. My data access is usually limited to about 1 month at a time. My directory structure options are,</p>

<p><code>1.</code> <code>FileSystem &gt; UserA &gt; 2010_01_01, 2010_01_02</code>, i.e., for each user, store each day's data as a file. and,</p>

<p><code>2.</code> <code>FileSystem &gt; UserA &gt; 2010_01, 2010_02</code>, i.e., for each user, store a months data as a file.</p>

<p>using <code>1</code> would mean when I fetching user data I have more frequent file open/close and fewer file reads(to get to the line I need) while using <code>2</code> implies less frequent file open/close and more file reads(to get to the line I need).
What would I be better off using?</p>

<p>Note: I realize with <code>1</code> that it is possible for me to access different files in different threads and probably speeding things up.     </p>
