I don't think it's a problem to run RAID0 for a backup volume... (after all, it is a backup and not the only existing copy) but it's not advisable to run your primary storage and your backup array both on the same RAID card or controller. If that card goes or somehow corrupts your volumes, then you are really up ***** creek.
I know you can use a RAID 0 as a backup, but I just don't trust it well enough for that purpose myself (JBOD can be done with the same drives, but offers a little more safety, as if a drive goes, you don't lose all the data on the set).
But to each their own.
There may be cases where a RAID 0 makes sense over JBOD, if you've so much capacity that the speed is necessary, and a better means (i.e. redundant RAID level) isn't possible for the backup set. Say a result of the lack of funds (it's just riskier IMO).
So I would suggest that if you are going to run 3 RAID0 arrays, then make sure your backup array is not on the same controller as your primary working array. Spread your risk around.
Given the listed equipment, this isn't possible, as a RAID controller can't run both RAID and JBOD simultaneously (you have to select between the two).
As it happens, the Areca is stable enough to do this (OS array + primary data array). Though your idea of separation to reduce risk is quite sound (and is done in the right environment, as the funds will be approved/made available for additional gear to do so).
Assuming the backup is kept to a stripe set, then it could be arranged so that the ARC-1212 handles both the OS and backup arrays, leaving the primary data array on the ICH10R.
There's risk with either method, but it's acceptable given the application IMO (near the limit though IMO, as I'm not a big fan of stripe sets to begin with; I tend to put the additional funds forth for rendunant arrays of some sort).
But assuming the backup is done via a JBOD, the SSD's should be run off of the ARC-1212, which means RAID ONLY. Thus the second pair of drives must use RAID as well, and 2 drives in this instance would be limited to a stripe or mirror (due to the lack of additional ports in order to support additional levels for the mechanical drives).
Also, If I was you, I would consider running the 4x2TB disks in a RAID10 array on the Areca. You get performance and redundancy. I would still backup critical stuff to a standalone drive but depending on the content and your risk tolerance, the RAID1 part of the RAID10 array might provide sufficient security to avoid having to backup anything or at least everything.
This is possible, as is a level 5 or 5 array. But I'm presuming that the capacity requirements means those levels aren't viable, and the budget isn't adequate to make it happen.
But it would be more advisable. At least a RAID 5 for the primary array, as you get a balance of redundancy, capacity and performance (better than 10 in regards to performance and capacity, though you do sacrifice some of the reliability, as a level 5 can only handle the loss of a single disk rather than a pair).
But such an instance would be beneficial to get a larger card (port count), as 2x SSD's + 3x mechanical could throttle the ICH10R,
assuming they're run simultaneously. If not, the smaller port count would be sufficient, but I'm figuring simultaneous access will be the case until informed otherwise.
Thanks for this suggestion. Thinking, how would Time Machine react if half of its "backup system" will lost in the case of one drive fail?
It should see less capacity, but still work (so long as the remaining capacity is adequate to hold the backup data). However, I've not tested Time Machine myself in this regard, so I don't know if it actually reacts the way other backup software does.
Do you mean, that ARC-1212 doesn't support JBOD and RAID at the same time?
Correct. You have a setting for RAID or JBOD mode on the Areca card, so it's not capable of both simultaneously. That's why the backup set is on the ICH10R if you go JBOD (Disk Utility can do JBOD).
Disk Utility is also capable of JBOD, and why you can use the ICH10R for that purpose, while using the ARC-1212 (or any other card that I've seen) for RAID.
Thanks for the links, never before seen those kind of external enclosures. Will put them behind of the ears for future needs. As I said on my first post, I'll using Hackintosh, so I've the
Fractal Design Define R2 case, which has eight 3,5" bays and two 5,25" bays.
As you're wanting to DIY your own system, you can select a case that will allow you to keep all the disks internally (cheaper too, just make sure you've an adequate PSU). As it happens, this case would suffice, with a little room to spare.
I use Lian Li myself, and stuffed in 17 3.5" disks (my RAID usage is under Windows though, not OS X).
I've thought this alternative too, but if I do 4x2TB disks in a RAID10, then I cannot use the features, what the Time Machine would offer to me; If I figure out, that yesterdays/nudiustertians (two days ago) video edit project is better than todays, so I can restore this project from the TM backup... And if I do 4x2TB RAID10 and want to use the TM, then I should buy more storage space (4-8TB), shouldn't I? Thanks for this suggestion, anyways.
If Time Machine is the limiting factor, then find better software (I've only used OS X as a single drive, as it's more of an experiment than anything else). Seriously.
Beyond this, I'd need much more information as to specific requirements and budgets.
For example:
Throughputs required
Capacity
Redundancy needs (if you know, otherwise it's likely to be RAID 5 as a bare minimum)
Disk count
Budget
Specific usage (this can help to fill in the holes for information, and aim you to the right solution)
