I was trying to get a server using a raid controller card up and running. I could not get the card configured right so i just installed the system strait onto a scsi drive.
Questions?
Is is nescessary to have the operating system on raid? Pros/Cons
Is it really difficult to go back later and try to convert to a raid? or
to install raid for data storage?
Obviously, RAID is there to protect you from disasters. The various RAID levels present you each a mix of disk space and safety level. If the server is critical I would definatively recommend RAID 1 (mirror disks) on the core OS components.
Upgrading to RAID afterwards will greatly depend on the RAID HW and OS. But usually you have an exhaustive list of 'RAID migration' paths and surely going from no RAID to RAID 1 should be possible.