I don't use veeam but I broke one or two of my lab vms with zimbra while doing snapshots (everything works fine until I recover the snapshot and MySQL wasn't able to start). I usually took snapshot without stopping sevices and without any kind of quiescing.
It's not a thing of big/small enviroment. If transactions are being made to the innodb and no precaution is taken with your dbs, that snapshot/backup will be as good as nothing.
My sugestion: stop/start zm services and if veeam gives you the option, do quiesce snapshots for the backup. It will take much longer then no-quiescing snapshots. You could also search for documentation regarding MySQL/openldap/etc backups with veeam...I only spoted problems with MySQL but you never know.
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