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I want data redundancy for my SSDs, and so would likely be using a software RAID like Windows Storage Spaces in a simple, fully-provisioned 2-way mirror configuration.

To minimize the risk of both SSDs failing at the same (or nearly the same) time, I was thinking of using 2 different SSDs - either from different manufacturer and/or different types (like SATA vs NVMe).

  • Aside from the likely differences in performance (especially in SATA vs PCIE NVMe scenario), are there any reliability issues I should be aware of?
  • Could a difference in performance (either due to different SSD type or different attachment or both) be in itself a reliability issue for a 2-way-mirror setup?
  • And would attaching one drive directly to the motherboard (say M2 extension) while attaching the other via external enclosure via USB 3 affect things in reliability sense?
  • If I am forced to use one of the drives through an external USB 3+ connection, what would be safer option: have a SATA SSD connected through an enclosure or have NVMe SSD connected through an enclosure?

I am just trying to come up with a sensible setup for average use case of Software-RAIDed SSDs (i.e. mostly reads, some writes, an advanced user scenario, but not db server or anything intensive like that).

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I would avoid mixing different drives. Select a reliable drive from a reputable manufacturer and put two of them in a RAID1 array.

As a general rule, try to not mix drives using different protocols (ie: SATA and NVMe, SAS and SATA, etc).

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  • Thank you for your answer. But could you elaborate. I mean if performance is not a concern, why is it a bad idea to keep one's eggs in several baskets so to speak? Why mixing protocols is bad? Due to constraints in my set up I may end up having to use one of the drives as external, i.e connected via USB 3+ through an enclosure of sorts.
    – Fit Nerd
    Sep 29 at 11:52
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    For software RAID, it mainly is a performance-related advise, as mixing SSDs/protocols can result in erratic performance. Hardware RAID (not your case, though) goes as far as forbidding most mixing. Anyway, if you plan to RAID on USB drives, performance probably is of (almost) no concern at all. Please note that many USB bridges have issues when heavily loaded, so I would strongly favor RAID between internal drives (of any sort - NVME+SATA is much better/faster/reliable than NVME+USB)
    – shodanshok
    Sep 29 at 12:07
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    One problem that comes to mind is a write hole. It could happen much more easily if you use protocols with significantly different characteristics. And this is too overcautious: just using two NVMe drives from different manufacturers is no less protected from simultaneous device failure than using devices designed for different protocols. So, you are going to suffer awful performance that USB has for absolutely no benefit. Just don't do this. And, if you still want to go that way, I'd warn you — no sane person will help you with such setup.
    – Nikita Kipriyanov
    Sep 29 at 12:07
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    Please notice that 10 Gbit/s USB3 has linear speed comparable to that of SATA 6Gbit/s, due to the nature of the USB protocol; but, as for random access it's a far, far worse than even SATA, due to very high inherent latencies. I wouldn't consider it as a viable protocol for a system drive that does more than "completely load into memory and work entirely from that". I tried it.
    – Nikita Kipriyanov
    Sep 29 at 12:12
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    If you don't have second NVMe slot on the MB it's still better to use passive PCIe adapter and second NVMe drive than SATA drive.
    – Nikita Kipriyanov
    Sep 29 at 13:14

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