USB3 SATA Enclosure w/Hardware Raid ?

1st Official Post

    New to NAS and PI and so pardon any ignorance on my part. I searched the forums but didn't find an answer to my question.




    I am setting up a NAS with a Pi 4 and OMV. I read the cautions about not running RAID over USB so I wasn't planning to go there. Is that RAID/USB issue related to the PI USB and/or OMV or is it a broader issue?


    As I looked at multi bay enclosures for my drives I noticed that some advertise as having "non RAID" or "Hardware RAID" options. Is that hardware RAID subject to the same RAID/USB issue or is its implementation in the drive bay device somehow outside or beyond the issue referenced in the OMV documentation?


    Thanks in advance for any feedback or clarification!
    Tom G.

    • Official Post
    Quote from Tom_G_2010

    Is that RAID/USB issue related to the PI USB and/or OMV or is it a broader issue?

    It isn't related to the RPi or OMV. It is a terrible idea to use raid on usb disks anywhere. And since the RPi can only use usb disks, raid shouldn't be used on it.


    Quote from Tom_G_2010

    Is that hardware RAID subject to the same RAID/USB issue or is its implementation in the drive bay device somehow outside or beyond the issue referenced in the OMV documentation?

    While a usb raid enclosure would work fine on an RPi, ask yourself why you really want something meant to add availability and redundancy to an RPi which has nothing to make it available or redundant. I will also throw in the standard "raid is not backup" comment.

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    Quote from ryecoaaron

    It isn't related to the RPi or OMV. It is a terrible idea to use raid on usb disks anywhere. And since the RPi can only use usb disks, raid shouldn't be used on it.

    While a usb raid enclosure would work fine on an RPi, ask yourself why you really want something meant to add availability and redundancy to an RPi which has nothing to make it available or redundant. I will also throw in the standard "raid is not backup" comment.

    Thanks for the quick reply!


    You suggested I ask myself why. Here's the why: Many moons ago I had one of those HP Home Servers with 4 drives in it. I had drive 0 and 1 mirrored for storing important files and it saved my bacon when drive 0 had a mechanical failure. So, I was thinking about that and hoping to mirror two drives for the same reason. I understand that the Pi is a single point of failure. But, my thinking was that if it craps out I don't suffer any information loss, but if a drive fails, I do.


    It is my understanding, again, total noob here, that Raid 1 would give me mirroring. Am I not understanding it correctly or barking up the wrong tree?


    Again, Thanks!
    Tom G.


    PS: Regarding overarching backup. I was also looking at other physical media and/or encrypted cloud storage for backup.

    • Official Post
    Quote from Tom_G_2010

    Am I not understanding it correctly or barking up the wrong tree?

    Raid 1 is mirroring but there are better options for low end equipment like an RPi. A scheduled rsync that runs hourly that syncs one drive to the other should be good enough to protect you. It is actually better in some situations - if you delete a huge directory, you could disable the rsync before it syncs to the other drive. If you were using raid 1, it would be gone instantly.

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    Like 1
    • Official Post

    I agree. RAID1 can, indeed, under some very specific circumstances protect your data. Specifically when one drive fail.


    But good backups provides data protection not just against a drive failure, but also against application bugs and against user errors and mistakes. So even if you decide to use RAID1 for some reason, you ALSO need backups to protect your data against common user mistakes.


    Yes, drives do crash and cause data loss. That is easy to acknowledge. But I would argue that most of us have lost more data to simple mistakes. Data loss through stupidity is less easy to admit to. And the main mistake is not having good backups the day something happens.


    If you have a couple of spare drives, use them for backups. Not RAID. Once you have good backups, feel free to add RAID, if you still, for some reason, feel that you need it.

    • Official Post

    I use a dual bay external USB enclosure with my RPi4. It has hardware RAID built into it. But I don't use that. Instead I use the two disks as separate filesystems. Works fine.


    And if something should happen with the enclosure, the data is still available. I am not so sure that the data would still be readable if the enclosure fail and I use the hardware RAID1 option. I suspect that I might need a spare enclosure, just in case...

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