= Scan on ingest =

''' Pro '''

 * Easy to implement

''' Con '''

 * New viruses won't be recognized


= Recurring batch scan =

''' Pro '''

 * Easy to implement
 * Runs when the servers are idle

''' Con '''

 * Scans unused files
 * Stresses local fileservers and uses bandwith for external resources


= Scan on access =

''' Pro '''

 * Only scans what needs scanning

''' Con '''

 * Hard to implement
 * Non-trivial realtime processing requirements