= Server-side file deletion =
Files are deleted from the data server's upload and download directories by the '''file_deleter''' daemon.
Typically you don't need to customize this.
The default file deletion policy is:

 * A workunit's input files are deleted when all results are 'over' (reported or timed out) and the workunit is assimilated.
 * A result's output files are deleted after the workunit is assimilated. The canonical result is handled differently, since its output files may be needed to validate results that are reported after assimilation; hence its files are deleted only when all results are over, and all successful results have been validated.
 * periodically remove 'antiques': output files that are older than the oldest WU in the database. These files are created when BOINC clients return after the corresponding WU has been deleted from the database.

Command-line options:

 -d N:: set debug output level (1/2/3)
 -mod M R:: handle only WUs with ID mod M == R
 -one_pass:: exit after one pass through DB
 -dont_retry_errors:: Don't retry file deletions that failed previously.
 -dont_delete_antiques:: Don't delete antiques
 -delete_antiques_interval S:: change the interval between delete antique passes (S in seconds, defaults to 24h)
 -delete_antiques_limit N:: change the maximum number of files deleted in one delete antique pass (defaults to 50000)
 -preserve_wu_files:: 	Update the DB, but don't delete input files
 -preserve_result_files:: Update the DB, but don't delete output files
 -dont_delete_batches:: Don't delete anything with positive batch number
 -input_files_only:: Don't delete output files.  If you store input and output files on different servers, you can improve performance by running separate file deleters, each one on the machine where the corresponding files are stored.
 -output_files_only:: Don't delete input files.
 -sleep_interval N:: Sleep for N seconds between scans (default 5)
 -appid N:: only process workunits with appid=N
 -app S:: only process workunits of app with name S

If the web-server account on your system is not 'apache',
add a {{{<httpd_user>}}} element to your [ProjectOptions#dirs config.xml] file.
Otherwise antique deletion won't work.

In some cases you may not want files to be deleted. There are three ways to accomplish this:

 * Use the -preserve_wu_files and/or the -preserve_result_files command-line options.
 * Include <no_delete/> in the [BoincFiles <file_info>]
 element for a file in a [WorkGeneration workunit or result template]. This lets you suppress deletion on a file-by-file basis.
 * Include nodelete in the workunit name. 

The antique files are deleted by using a Unix 'find' command to locate files that are older than the oldest workunit. The find command will work on NFS mounted file systems, and will ignore .nfs stale file markers. The output of find is limited by a 'head' to 50000 files by default.