Raid5 Error

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    • Raid5 Error

      First of all, let me say I know Raid 5 on USB drives is not a good idea. It's just something I want to play around with and isn't a real solution, but I'd like to get it to work and see how it is. That being said, here's my issue.


      Forgive me if I'm doing something wrong, but I'm new to OMV. I am trying to set up Raid5. I have 4 USB hard drives. I went into physical disks and I've wiped them all clean. They are attached to a powered 7-Port USB hub plugged into My RasPi-3. All drives are recognized. Once I go into Raid Management, Create a new raid, name it, select all the drives and hit create, I get this error:


      Failed to execute command 'export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export LANG=C; omv-mkraid /dev/md0 -l raid5 -n 5 -N USBStorage /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde 2>&1' with exit code '1': mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: chunk size defaults to 512K mdadm: size set to 488222720K mdadm: automatically enabling write-intent bitmap on large array mdadm: unexpected failure opening /dev/md0

      I've scoured the web trying to fix this on my own but to no avail. If this is something easy that I'm overlooking, I apologize for my ignorance, but as I said, I'm new to OMV and Linux. Any help is appreciated.Additional InformationFailed to execute command 'export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export LANG=C; omv-mkraid /dev/md0 -l raid5 -n 5 -N USBStorage /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde 2>&1' with exit code '1': mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: chunk size defaults to 512K mdadm: size set to 488222720K mdadm: automatically enabling write-intent bitmap on large array mdadm: unexpected failure opening /dev/md0
    • jwiles68 wrote:

      First of all, let me say I know Raid 5 on USB drives is not a good idea. It's just something I want to play around with and isn't a real solution, but I'd like to get it to work and see how it is.
      But you probably aren't going to get it to work and it would never be a good representation of raid 5 ESPECIALLY on an RPi. Please don't waste your time trying this. If you want to experiment with raid 5, use virtualbox on your desktop and install OMV. Most people don't need raid anyway.
      omv 4.1.6 arrakis | 64 bit | 4.16 backports kernel | omvextrasorg 4.1.7
      omv-extras.org plugins source code and issue tracker - github.com/OpenMediaVault-Plugin-Developers

      Please read this before posting a question.
      Please don't PM for support... Too many PMs!
    • jwiles68 wrote:

      They are attached to a powered 7-Port USB hub plugged into My RasPi-3.
      Sorry to be that harsh but you should not use RAID since you fail to understand the whole principle. This hub is a very prominent 'single point of failure' and relying on it means implementing the worst RAID setup possible. Any glitches happening here and your whole array is gone instantly. Also a RAID5 tries to compensate from a single instantly dying disk (it's not working that way, most disks fail differently) in a way that you can replace this disk with another one to then let a resync/rebuild happen without disruption of service. The only goal of such a setup is availability. Who needs this at home? Do you run a business on your RPi 3 that you need business continuity? Such a resync/rebuild is an enormous amount of stress for all components and if anything fails at this stage again your whole array is gone.

      You can't increase reliability by throwing together a bunch of totally inreliable hardware pieces (your Raspberry Pi being the worst one already -- please let in a SSH session run 'raspimon' in parallel while you try to access disks and post the output)
    • Thank you for your input and the links. I DO understand the principle of all levels of Raid. I already have a NAS storage device running Raid 1. (2 different hard drives. Not USB drives.) I understand also the single point of failure running this on a 7 port USB hub ESPECIALLY through a RasPi and the tremendous amount of work load this would put on all components.

      It was just for the hell of it. To see if I could. I knew I'd run into problems, and I wanted to work through them. That's how we learn. anyway, thanks for the advice. Sorry for wasting your time.
    • jwiles68 wrote:

      It was just for the hell of it. To see if I could. I knew I'd run into problems, and I wanted to work through them. That's how we learn. anyway, thanks for the advice.
      I get it. I was just saying that if you want to learn, don't use an RPi. raid is a nightmare on it and I didn't want you to waste your time.
      omv 4.1.6 arrakis | 64 bit | 4.16 backports kernel | omvextrasorg 4.1.7
      omv-extras.org plugins source code and issue tracker - github.com/OpenMediaVault-Plugin-Developers

      Please read this before posting a question.
      Please don't PM for support... Too many PMs!
    • jwiles68 wrote:

      I knew I'd run into problems, and I wanted to work through them.
      Well, 'unexpected failure opening /dev/md0' -- this is what the try to create the array already results in. Raspberries are prone to underpowering issues so if already creation of an array fails... what to expect next?

      I suggested to you executing raspimon for a reason -- to be able to learn something (at least avoiding this platform for anything serious wrt storage). If you use latest official OMV image for Raspberries you could also provide output from 'armbianmonitor -u' (uploads debug logs to an online pasteboard service where maybe some more details are available). But trying to play RAID on a Raspberry is of no use anyway (except data loss for sure).
    • Alright, one last question guys and I won't waste any more of your time. What about using LVM to combine those drives. I thought I read somewhere, where it may fill up one drive first, before moving on to the other. I've got these drives, but I don't want 5 separate drive letters for each drive. I'd rather just have one share.

      I'm not at all concerned with the data on there. It's gonna be music, movies, tv shows etc. that I already have backed up, or could get back if I really wanted.
    • jwiles68 wrote:

      Alright, one last question guys and I won't waste any more of your time. What about using LVM to combine those drives. I thought I read somewhere, where it may fill up one drive first, before moving on to the other. I've got these drives, but I don't want 5 separate drive letters for each drive. I'd rather just have one share.
      Use the unionfilesystem plugin (mergerfs). It does just that. If a drive dies, you only would need to restore from backup the data from the drive that failed.
      omv 4.1.6 arrakis | 64 bit | 4.16 backports kernel | omvextrasorg 4.1.7
      omv-extras.org plugins source code and issue tracker - github.com/OpenMediaVault-Plugin-Developers

      Please read this before posting a question.
      Please don't PM for support... Too many PMs!