NAME

       atopacctd - process accounting daemon

SYNOPSIS

       atopacctd [-v | topdirectory]

DESCRIPTION

       The  atopacctd daemon switches on the process accounting feature in the kernel and let the
       process accounting records be written to a file, called the source file from  now.   After
       process  accounting  is activated, the atopacctd daemon transfers every process accounting
       record that is available in the source file to a shadow file.  Client processes (like atop
       processes) will read the shadow files instead of the process accounting source file.
       In  this  way,  the  atopacctd daemon operates as a 'layer' between the process accounting
       file that is written by the kernel and the shadow accounting files that are read  by  atop
       processes.

       This approach has the following advantages:

       o  The  atopacctd  daemon  takes  care that the source file is kept to a limited size.  As
          soon as its maximum size is reached, it is truncated to a size of zero again  (this  is
          not noticed by the atop processes).

       o  The  atopacct  daemon takes care that a shadow file is kept to a limited size.  As soon
          as the current shadow file reaches this maximum size, the atopacctd  daemon  creates  a
          new  (subsequent)  shadow  file.   While client processes still have the possibility to
          read the previous shadow file(s), the atopacctd  daemon  continues  writing  accounting
          records  to  the  newest  (current) shadow file.  For this reason, the name of a shadow
          file consists of a 10-digit sequence number followed by the extension  '.paf'  (process
          acounting  file).  Old shadow files that are not used by client processes any more, are
          automatically removed by the garbage collector in the atopacctd daemon.

       o  When no client processes are active (any more), all shadow files will be deleted and no
          records  will  be transferred to a shadow file any more. As soon as at least one client
          is activate again, the atopacctd daemon continues writing shadow files.

       The directory /run is used as the default topdirectory.   Below  this  top-directory,  the
       source  file  pacct_source  is  created  to which the kernel writes the process accounting
       records.
       Furthermore, the subdirectory pacct_shadow.d is created as a 'container'  for  the  shadow
       files.   Apart  from  the  shadow  files,  also  the  file  current  is maintained in this
       subdirectory, containing the sequence number of the current (newest) shadow file  and  the
       maximum number of records that will be written in each shadow file.

       An  alternative  topdirectory  can  be  specified  as  command  line  argument.   When  an
       alternative topdirectory is defined, also modify the  configuration  file  /etc/atoprc  to
       inform  atop  clients  about  this  alternative  location (see the atoprc man page).  Such
       alternative topdirectory should be owned by root and may not be writable for the group  or
       others (security reasons).

       Notice  that the kernel suspends writing process accounting records when the free space of
       the filesystem on which the process accounting file resides drops  below  2%.  Writing  is
       resumed  when  the free space is 4% or more.  These lowwater and highwater percentages can
       be configured via the /proc/sys/kernel/acct pseudo-file.
       The atopacctd daemon suspends transferring process accounting records to shadow files when
       the  free space of the filesystem on which the process accounting file resides drops below
       5%. Transfer is resumed when the free space is 5% or more.  Log messages are generated via
       syslog when writing to the current shadow file is suspended or resumed.

       The -v flag can be used to verify the version of the atopacctd daemon.

FILES

       /run/pacct_source
            Regular  file  to  which the kernel writes the process accounting records.  This file
            will be regularly truncated.

       /run/pacct_shadow.d/current
            Regular file containing the sequence number  of  the  current  shadow  file  and  the
            maximum number of records per shadow file.

       /run/pacct_shadow.d/N.paf
            Regular  files  containing  the  process  accounting  records  that  have been copied
            transparently from the source file (N represents a 10-digit sequence number).

SEE ALSO

       atop(1), atopsar(1), atoprc(5), netatop(4), netatopd(8)
       http://www.atoptool.nl

AUTHOR

       Gerlof Langeveld (gerlof.langeveld@atoptool.nl)