Comments and maintenance intervals are now saved together with other information in the status and retention file. These special files and the accompanying parameters
comment_file have been removed from Nagios 3.0. With an upgrade from Nagios 2.x to this version you can keep any existing comments and maintenance intervals—how to do this is described in H.13 Upgrade from Nagios 2.x to 3.0.
A further change involves the commenting of acknowledgments. Until now, non-persistent acknowledgments were deleted with every restart. In Nagios 3.0 they now survive; the system deletes the comment for an acknowledgment only when the problem has been rectified, so that the service or host status is ...