You could just copy data between two seafile servers via seafile client or web, but life's to short for that.
If you want to play around with mikrotik or a need a mikrotik CHR, you can install it on XEN and run it without any issues.
Happy times with locales during a simple upgrade Error: The locale requested by the environment is invalid. Error: Could not create target cluster
Switching mailserver with lots of active users isn't an easy task. First you need to copy the mails to the new server and then get all the users to change mailserver settings at the same time to switch to the new server.
Adding new disks to a LSI controller, creating a new VD and extending an existing LVM volume group