Help with using rsync and cron?

[gundamguy]

So I was reading the general announcement thread for the 6b12 release and noticed some advice about using rsync and cron to create an automated backup of designated directories. Link

 

Now I think this is a really cool idea and highlights some powerful tools which Lime Technology gave us but because I am a Linux noob I have a few questions about this before I start writing a script.

 

First: Are there any common mistakes, misconceptions, best practices or pitfalls with rsync? Any attributes I should always use or never use, or should use in specific cases which would be common to unRAID usage?

 

Second: Is there any possible issues with running rsync via cron to automatically backup some appdata folders on my cache disk to a back-up folder on my array? Think of Plex Installs, would plex running, or even being used to stream info while this rsync job started use cause problems?

 

Third: Is there any issues with using a cron script activated rsync if a powerdown is triggered by a UPS power failure  shutdown while the rsync is in progress. Would rsync prevent unRAID from powering down? What if you have the powerdown plug-in, would this allow for a safe powerdown, would this cause issues with rsync / data corruption?

 

I'm a curious kind of guy, but I don't really know much about rsync or cron, so any help would be much appreciated.