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Summary

This article describes how to reset access time and ignore change time on UNIX backups.

 

 

Resolution

 

 

By default, the access time (atime) of files on a UNIX server is updated by a backup.

 

 

Also by default, DPX uses both the modified time (mtime) and the change time (ctime) of a file when determining if it is selected in an incremental (INCR) or differential (DIFR) backup.

It is possible to tell DPX to reset the atime after backup by setting a parameter that resets the atime during backup. This "atime-reset" updates the ctime of the files. As a result, DPX uses only the mtime on a UNIX node for incremental and differential backups.

To enable this:

  1. Edit the DPX startup script dpx/bin/sscmagent.
  2. In the section marked "# Set DPX directory & parameters," enter the following statement:

    SS_ATIME="1"; export SS_ATIME
     
  3. When no jobs are running, stop and start the cmagent (sscmagent stop, sscmagent start).

In summary, when the SS_ATIME environment variable is set:

  • The atime of files will not be changed as a result of the backup.
  • The ctime of all files backed up will be changed.
  • The ctime of all files will be ignored when data is selected for incremental and differential backups.