title: Setting wal_keep_segments for PostgreSQL hot_standby
body: <p>I am having a trouble setting up a PostgreSQL hot_standby. When attempting to start the database after running pg_basebackup, I receive, <code>FATAL:  could not receive data from WAL stream: ERROR:  requested WAL segment 00000001000006440000008D has already been removed</code>, in the postgresql.log. After a brief discussion in IRC, I came to understand the error likely originates from a too low <code>wal_keep_segments</code> setting for my write intensive database.. </p>
  
  <p>How might I calculate, if possible, the proper setting for <code>wal_keep_segments</code>? What is an acceptable value for this setting?</p>
  
  <p>What I am working with:</p>
  
  <ul>
  <li>Postgresql 9.3</li>
  <li>Debian 7.6</li>
  </ul>