I've just switched from a NAS to a Pegasus Raid system. I would the NAS did give me countless reminders to make sure I did SMART testing on the drives and regular data scrubbing.
Regarding Media Patrol, Redundancy Check and Synchronisation.
Which of these should I run if needed and how often?
I'm assuming Media Patrol is the smart test and redundancy sounds like scrubbing so what is Synchronisation?
Do they take many hours to complete and if I shutdown the Pegasus will they continue when it restarts?
media patrol is an automatic routine check with your raid system.
You can switch it on or off.
We don't run it at all. We didn't have serious problems for years - just
a bad drive here and there. The rebuilt was never a problem. All of our raids
are on raid level 6 plus spare. After 5 years or 50.000 working hours,
we swap the complete drives for new ones and use the old drives as
Mac pro 8core
several raid systems
Ranier offers excellent advice. Promise supplies the truly horrible Toshiba SATA drives. At some point, you should swap out all the drives for WD RED, or HGST NAS drives - both which are not very expensive and certainly more reliable.
I would not worry about the Maintenance Routines. Even with the Toshiba drives, the rebuild process works quite well.