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    mdadm in 2018 ??

    IT Discussion
    mdadm software raid linux storage
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    • DustinB3403D
      DustinB3403 @FATeknollogee
      last edited by

      @fateknollogee said in mdadm in 2018 ??:

      @dustinb3403 said in mdadm in 2018 ??:

      The rebuild portion was a pain in the ass, as the system I had at the time didn't have hot swap, so I had to power down to replace disks.

      It's possible but just a huge pain.

      You did not have auto-rebuild?

      I didn't because it simply wasn't worth it for us, 4 disks, OBR10.

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      • scottalanmillerS
        scottalanmiller @FATeknollogee
        last edited by

        @fateknollogee said in mdadm in 2018 ??:

        Auto-rebuild should be automatic once I swap out the failed drive.

        This is called blind swap and it is NOT a good idea. The system does not know how you want the new drive to be used, there is a reason it does not do this. RAID is more complicated than that. If you want MD RAID to do things like that (MDADM is the management utility, not the RAID) you have to cripple it and make it a lot less flexible than it is today.

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        • scottalanmillerS
          scottalanmiller @FATeknollogee
          last edited by

          @fateknollogee said in mdadm in 2018 ??:

          All the FOSS fan boi's say everything is easier in Linux vs Windows.

          It is. find any way to do any of this easier on Windows? Given that Windows doesn't even have a production level software RAID facility, that alone proves that this is easier on Linux than on Windows.

          Simple rule: hard is always easier than impossible. Impossible is just infinitely difficult. Linux here is hard, Windows is impossible.

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          • scottalanmillerS
            scottalanmiller @FATeknollogee
            last edited by

            @fateknollogee said in mdadm in 2018 ??:

            Again, I repeat, it must be easy to use!!

            Windows has nothing easy to use, this is unrealistic to demand that Linux not only blow Windows away in functionality and be dramatically easier - but must additionally be arbitrarily "easy" on top of being easier. It's a great thing to want, but not reasonable to demand. Would anyone ever demand something like that of Windows? Of course not.

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            • scottalanmillerS
              scottalanmiller @FATeknollogee
              last edited by

              @fateknollogee said in mdadm in 2018 ??:

              Auto rebuild upon swap ?

              No software RAID does this, and only some hardware RAID. If you want this functionality, you script it yourself as you have to include the rebuild assumptions into your script. MD has no way to know the intentions of the added drives, so a rebuild might be something other than what is desired.

              I agree, it would be nice if blind swap had a simple GUI to configure. The problem with blind swap is places that want it generally aren't willing to configure it. So the same answer on Linux as on Windows - use hardware RAID with blind swap assumptions built in. Linux can do everything that Windows can do, and more, as easy or easier.

              You can do it identically to the Windows way, or you can do it other ways too. Just more options, nothing given up.

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              • scottalanmillerS
                scottalanmiller @FATeknollogee
                last edited by

                @fateknollogee said in mdadm in 2018 ??:

                @dustinb3403 said in mdadm in 2018 ??:

                The rebuild portion was a pain in the ass, as the system I had at the time didn't have hot swap, so I had to power down to replace disks.

                It's possible but just a huge pain.

                You did not have auto-rebuild?

                You'll need to define this behaviour. No reason it can't be done, but you can't just say "auto-rebuild", that's not enough info. As a human, I would not know from this for sure how you want the system to behave. It's quite complex what you are asking for. There is a bit to consider. For an individual environment, it's fine to make assumptions and script it to work the way that you want it, but you have to understand that what you want is not generic and there is a reason that the rest of us do not want it or look for it. I totally understand why you probably want it, but it's not as simple as choosing to have it or not have it. And there is a reason that literally no software RAID implements it... not MD, not ZFS, not Windows, etc.

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                • black3dynamiteB
                  black3dynamite
                  last edited by

                  For monitoring md raid, there’s a template for md raid using Zabbix.
                  https://share.zabbix.com/cat-server-hardware/template-md-raid

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                  • scottalanmillerS
                    scottalanmiller
                    last edited by

                    Here is a good example of why this is complex even for blind swap hardware RAID... it's not always clear what it is supposed to do.

                    https://mangolassi.it/topic/17314/replaced-drive-in-pe-t410-not-adding-to-virtual-disk/

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