More full backups per week than specified in backup schedul

[giggety]

Fellow Zimbra users and administrators,

I'm running across an interesting scheduling issue with my Zimbra backups. Currently, the backup schedule is set so that full backups take place at 4am every Saturday morning, and incremental backups take place at 4am Sunday - Friday mornings.

This schedule is confirmed both by zmschedulebackup -q:

===========
i 0 4 * * 0-5 -a all
f 0 4 * * 6 -a all
d 6m 0 0 * * *
===========

as well as via the zimbra user's crontab:

===========
0 4 * * 0-5 /opt/zimbra/bin/zmbackup -i -a all
0 4 * * 6 /opt/zimbra/bin/zmbackup -f -a all
0 0 * * * /opt/zimbra/bin/zmbackup -del 6m
===========

Due to the size of our /opt/zimbra partition, we have a script which shunts off any existing full and incremental backups to an NFS-mounted volume for safekeeping, and to clear space for new backups. This runs every few days.

What I am noticing, however, is that the Zimbra server is doing a full backup every other night (and sometimes two consecutive mornings in a row), rather than on the schedule indicated above.

What would be causing the Zimbra server to run full backups on days which are not specified for full backups like this?

Thanks very much for your help, and let me know if I can help provide any further information.
Jadrian Johnson

[bdial]

if you add a user, the next time any backup runs it does a full backup of just that user because it has to have a full one to do an incremental.