Thread: Striping (RAID 0) JBOD arrays together?

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  1. #1 Striping (RAID 0) JBOD arrays together? 
    Senior Member Mark K.'s Avatar
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    Hey guys,

    I'm wondering if anyone could help me understand how JBOD can interface with striping/RAID 0 (if at all)?

    I've got 6x 1TB M.2 drives en route and already have 2x 2TB M.2 drives, and I want to stripe them all together. Is it possible to use JBOD to turn the 6x 1TB drives into 3x 2TB JBODed drives, and then stripe those three JBODed 2TB arrays with the two natively 2TB drives - to create a striped 10TB RAID?

    I've Googled up, down and all around, but can't find any clarity on the question.

    Cheers,

    Mark
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  2. #2  
    Senior Member Alex Lubensky's Avatar
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    Basically you can't do a RAID over another RAID - you have different standards for that, called like 10 (1+0), 15 (1+5) etc.

    But, I don't recommend use of RAID 0. It's basically a 200% more dangerous solution compared to the use of single drive (if one drive fails you loose information from both drives). I've had a drive which was ejected from RAID 0, was still working but couldn't recompile back into raid 0, wharever was done (depends massively on RAID drive - is it sofrware or hardware etc etc etc). So I've lost a whole 2 drives of media in a moment. Just because of a program error, not even a hardware one.
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  3. #3  
    Senior Member Mark K.'s Avatar
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    Quote Originally Posted by Alex Lubensky View Post
    Basically you can't do a RAID over another RAID - you have different standards for that, called like 10 (1+0), 15 (1+5) etc.

    But, I don't recommend use of RAID 0. It's basically a 200% more dangerous solution compared to the use of single drive (if one drive fails you loose information from both drives). I've had a drive which was ejected from RAID 0, was still working but couldn't recompile back into raid 0, wharever was done (depends massively on RAID drive - is it sofrware or hardware etc etc etc). So I've lost a whole 2 drives of media in a moment. Just because of a program error, not even a hardware one.
    I have redundancy, so I'm not worried about a striped array going bad. It's just for storing my online media.

    I'm familiar with the various RAID standards and what each is capable of. What I'm trying to find out is whether you can span two 1TB drives together (to form a 2TB drive) and then stripe that JBODed drive together with a natively 2TB drive?
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  4. #4  
    Senior Member Alex Lubensky's Avatar
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    That's exactly what I was telling you - nope, generally you can't do a Raid in another Raid. There are nested RAID levels for this instead: https://en.wikipedia.org/wiki/Nested_RAID_levels

    also there are these: https://en.wikipedia.org/wiki/Non-standard_RAID_levels

    Maybe some controller or a virtual machine exists for this task, but it is not common. Literally to achieve the thing you want is to make a software RAID 0 with a hardware raid 0 inside of it. You can do a virtual drive instead also.
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  5. #5  
    Senior Member Simon Dunne's Avatar
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    You're going back in time to SAN architecture and LUNS. As Alex said, it's not really possible and not even worth it anyway. Put all 6 disks in RAID5, then if you lose one, you'll be fine to continue working (rather than having to reload from archive) and your speed using M.2's will be blazing anyway.
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  6. #6  
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    Yeah, RAID5 is better for speed, as it'd increase read performance by 3x (presuming the array is four hard drives) vs. 2x of RAID0/RAID10, and still gives redundancy (at the expensive of only one drive's worth of capacity).

    Conversely RAID10 requires four disks and is what you're describing; two mirrored/striped arrays (half the capacity of all four drives, double the read/write performance, and redundant).
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