There are a few different logs for the Redstor Online Backup Plus client that you may be required to send.
Win2003/XP: C:\Documents and Settings\All Users\Application Data\Redstor Limited\RedStor Online Backup Plus\logs
WinVista/7/8/2008/2012: C:\ProgramData\Redstor Limited\RedStor Online Backup Plus\logs
Linux: /opt/Redstor Limited/var/log/
Mac OSX: /Library/Logs/Redstor Limited/RedStor Online Backup Plus
Within will be a separate folder for each log type.
These may be requested as well, you can find them by going to the local server and placing in the following URLs.