The following is the list of files you should not edit by hand. openmediavault has complete control over these files and any changes will be overwrriten on demand.
/etc/fstab This file contains all mount entries, physical and network ones. openmediavault identifies them by using the «openmediavault» tags, in between those you should not delete entries or change options. Any new mount drive or network entry will rewrite fstab in between those lines, reverting any changes you have done. Please refer here for editing options of fstab entries. You can add any content you want outside the tags.
/etc/network/interfaces The explanation is already in the FAQ
POSTFIX: Any configuration files by postfix should not be edited unless you know what you are doing. You run the risk of breaking the notification system.
/etc/samba/smb.conf Use the extra options in general or by share to define directives not present in the webUI.
/etc/proftpd/proftpd.conf Use the extra options in general or per share to add directives not available in the webUI.
/etc/exports Use environmental variables if you want to change the pseudo root filesystem options for NFSv4.
/etc/apt/sources.listThis is default debian repository server file. Read more information here.
/etc/apt/sources.list.d/openmediavault.listThis is the server package repository for OMV.