I have an old Mac Pro, with 10.8.5. I'll have to update to Yosemite in the following weeks.
But...I have an internal 4 disk RAID0 - scratch space, and temporary usage- and an external 8 disk RAID6 controlled by an Areca 1680x.
The OS itself is on a separate SSD. Should I be worried, that after the OS update the internal or the external RAID will disappear?
The short answer is yes, you ALWAYS need to be concerned when updating or upgrading a working system to a new OS, because you may need newer drivers for your hardware components that either may not exist yet, or simply may not yet be perfected. So, ALWAYS clone your boot drive to an external FireWire drive first, using SuperDuper or Carbon Copy Cloner.
David Roth Weiss
David Weiss Productions
David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.