RAID5 in MacOS X

Readers regularly write to us for help after experiencing a broken hard drive or lost data. It's not till then painfully obvious that making regular backups is indispensable as nobody is safe from failure. But making copies takes time. You'll think of it at the beginning, but little by little you find that you haven't made any copies for weeks, then months, then years, until the day when a disk fails. In order to never have to think of it again, there are two solutions: to have an application or a script which does it all for you, or to use hard drives configured in RAID in order to secure itself against a breakdown. We have already done an article on software RAID, which is available here.
Mac OS X, by default, can only manage RAID 0 and RAID 1 in software. Which means that the processor of the computer is used to manage the RAID, thus loosing a little computer performance. To avoid that, it is possible to use hardware RAID, which has an additional processor (or RAID controller) which manages the created RAID volume. But then the following problem comes up: which card with a RAID controller to choose? Indeed, it's only possible to find RAID 0 or RAID 1 controllers for the Mac. No hardware solution exists for RAID 5, at least in PCI (I've found just one PCI-X card, but it's not compatible with previous machines like a PowerMac G4), although there are thousands of cards for a PC running Windows or Linux. Not particularly wanting to create a Linux server (and Windows server even less..), I was thus left to search for a hardware RAID 5 solution for a PowerMac G4.
There are external boxes which can already do this, for example the products offered by our partner Macway. It is also possible to use a NAS, but that is not really what I want to do. My goal is to be able to use my "old" PowerMac G4 and to to know if it is really possible to run a hardware RAID 5, as opposed to what Apple states.