Zimbra Forums

I'm developing a script to do monthly backup of the zimbra directory (/opt/zimbr).
# sudo -u zimbra /opt/zimbra/bin/zmcontrol stop
# tar -zcvf /var/zimbra/archive/zimbra_bk_$(date +%F).tar.gz /opt/zimbra
# sudo -u zimbra /opt/zimbra/bin/zmcontrol start
Then I run into error on the service start up...
Host mail.yius.ca
Starting ldap...Done.
Starting zmconfigd...Done.
Starting dnscache...Done.
Starting logger...Failed.
Starting logswatch...failed.

Starting mailbox...Done.
Starting memcached...Done.
Starting proxy...Done.
Starting amavis...Done.
Starting antispam...Done.
Starting antivirus...Done.
Starting opendkim...Done.
Starting snmp...Done.
Starting spell...Done.
Starting mta...Done.
Starting stats...Done.
Starting service webapp...Done.
Starting zimbra webapp...Done.
Starting zimbraAdmin webapp...Done.
Starting zimlet webapp...Done.
Starting imapd...Done.

After some manual intervention, I've managed to get all the services restarted normally.
This is a plain!! That's means I can't automate the script in a cron job.
Question:
Why won't the services fail to restart after tar'ing the zimbra directory?
Is some happens in the tar process can corrupted the zimbra system?