My advise: Don't bother "learning RAID controllers".
Im afraid I have to agree with this advice. In the presence of software like ZFS (from Sun) and LVM (from IBM's AIX), with easy availability of NAS, SAN and cloud storage, the arguments in favor of hardware RAID local to a server become much thinner. What drives that change is the evolution of hardware and networking, not so much the software. Both ZFS and LVM are now 20 years old, very mature software.
Grüße,
Sven.
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Sigmentation fault. Core dumped.