Question about RAID

in Genius Bar edited January 2014
I have a question regarding RAID.

I have two 500GB discs, which are configured through hardware (firmware), as RAID 0 (striped), effectively making a fast, 1GB volume.

I have another two 500GB discs which are just drives in separate enclosures. Utilizing Apple's Disc Utility, is there any advantage or disadvantage of selecting RAID 0 vs. Concatenate (which seems to be Apple's version of JBOD)?

I understand Concatenate is useful when I have just a splat of discs in all different sizes, and I want to use multiple physical drives as one logical volume, without loss of storage. Whereas RAID 0 requires all drives to be of the same size. Since I am using 2 physical drives which are identical in terms of size, is there any advance to Concatenate or should I use RAID 0 as I plan?

2 * 500GB = 1GB storage / RAID 0 through hardware.

2 * 500GB = 1GB storage / RAID 0 or Concatenate through Apple Disc Util.

The last thing I would like to do, is set up all four drives as RAID 1 (mirrored), so I end up with RAID 0 + 1, utilizing 4 physical 500GB drives, giving me a total of 1GB useable storage.

Any suggestions/input/comments before I go ahead and do this? I am new to using Apple's software implementation of RAID, is there anything I should be aware of beforehand (like for example: "it's completely broken and doesn't work right! Your fast redundant drive pool turns into worthless scrap metal the instant a single drive fails! Oh, by the way, there's also no notice when the drive fails!" <-- would be nice to know beforehand).

In line with that thought ^^^ in THEORY what I want to do will work fine, but in the real world, would I just be better off leaving 1GB of disc at RAID 0 through hardware, the second set at RAID 0 through Apple's software, and then just use SuperDuper! to clone one set to the other every 24 hours? This solution is slightly less perfect, since it's not "instant", but at most I stand to lose 23 hours worth of changes to the filesystem, which is bad but tolerable if it increases the overall stability/reliability.

BTW- I realize the "right" solution is probably getting a SATA card and a dedicated RAID enclosure that slots 4-5 drives and does all this through hardware and I may eventually do that. Where I'm coming from is more along the lines of, I've got all these disks laying around, all of them are 7200RPM, 16MB cache, 500GB, all of them are FW800, all of them are sitting on my desk, why don't I do something to cut down on the # of disks I have mounted and simplify my backup process.

Thank you
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