Raid 5 growing

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    • OMV 3.x

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    • Raid 5 growing

      Hello all
      Another noob here with hopefully an easy question.

      So I used 4 8tb drives and used OMV to set them into a Raid 5. I like the software and the speed of the NAS so I now have 2 More 88tb drives to add so I want to grow the array.

      So my question would be. Can I add both new drives at once then tell OMV to grow the array? Or do I have to add one disk and grow the array and then repeat with the second new drive?

      So can I add them both at once or do I have to add them one at a time?

      Thanks for any help in advance. Just getting my self sorted so when the drives get here I can install them and actually do it correctly.

      :)
    • RobertR728 wrote:

      /--/ I like the software and the speed of the NAS so I now have 2 More 88tb drives to add so I want to grow the array.

      So my question would be. Can I add both new drives at once then tell OMV to grow the array? Or do I have to add one disk and grow the array and then repeat with the second new drive?

      /--/

      Believing that it's possible, I looked at the operation using a VM with 6 virtual hard drives. I started with 3 disk RAID5 array and added two drives at the same time.

      It worked in the one instance where I tried it (I can't emphasize that enough - one try) with the following command line:


      mdadm --grow /dev/md0 --raid-devices=5 --add /dev/sde /dev/sdf

      (depending on your array name and devices, this command line may need modfication.)

      Would I do the above with a working system, without FULL backup of the data on the array? Not a chance in, well,, "the hot place". First, virtual 5GB hard drives (tiny) are not real 8TB hard drives. And, notably, the reshape from 15GB to 25GB took roughly 10 minutes, with no data on the array. Finally, note that this single outcome, in a VM and with no data, is not realistic. This may or may not work with real hardware.

      Depending on the existing data on the array, the operation may take days which will be a non-stop torture test of the existing drives. If your existing drives have significant age on them, a failure is possible in the process.
      ______________________________________________________________________________

      My advice would be, back up your irreplaceable data before doing anything and, if you must grow the array, do it one drive at time.
      Good backup takes the "drama" out of computing
      ____________________________________
      OMV 3.0.99 Erasmus
      ThinkServer TS140, 12GB ECC / 32GB USB3.0
      4TB SG+4TB TS ZFS mirror/ 3TB TS

      OMV 3.0.99 Erasmus - Rsync'ed Backup
      R-PI 2 $29 / 16GB SD Card $8 / Real Time Clock $1.86
      4TB WD My Passport $119

      The post was edited 1 time, last by flmaxey: edit ().

    • RobertR728 wrote:

      Does the array go offline while it is growing. Or Does it continue to file share while it's rebuilding?
      It stays online but accessing can greatly slow down the rebuild.
      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

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    • lol I noticed spell correct was changing it to 88tb I thought I caught them all . lol

      Okay I have to edit this because I can't find the time it takes to add a drive to the array. I shutdown and installed one new 8tb drive. Booted up logged in thru root gui. Wiped the new drive then hit grow and selected the new drive and added it to the array. Hit save then apply pops up so I apply. It appears to apply but I don't see anywhere thru the gui to see the progress of the addition of this drive to the array.
      So someone please tell me where to look for the status of this operation. Because i looked thru every page and I can't see it. :(

      So another update. Apparently my raid growing did not start when I hit grow. I found the info area of the array and it showed five disc now. But the new one I just put in was called a spare.
      So with done research I found this command.

      mdadm --grow /dev/mdX --size=max

      After running that I now see where it says reshaping and in have a processor load now which I didn't before. So I'm thinking it's success on getting it started. And hopefully since these are pretty new drives there won't be any failures growing the array.

      Thank you to all that helped and commented. I really do appreciate the help.

      Robert

      The post was edited 3 times, last by RobertR728 ().

    • cabrio_leo wrote:

      RobertR728 wrote:

      2 More 88tb drives
      Where can I buy such big drives? :D
      100TB drive. Here you go! :)

      Since they're not disclosing the price yet, I hope you have a few extra Euro's...
      Good backup takes the "drama" out of computing
      ____________________________________
      OMV 3.0.99 Erasmus
      ThinkServer TS140, 12GB ECC / 32GB USB3.0
      4TB SG+4TB TS ZFS mirror/ 3TB TS

      OMV 3.0.99 Erasmus - Rsync'ed Backup
      R-PI 2 $29 / 16GB SD Card $8 / Real Time Clock $1.86
      4TB WD My Passport $119
    • Good lord that is a huge hard disc. Just imagine the day for the world of computers that those type drives are common place. Or we are swapping them out like floppy discs of the days past. Exciting and scarry at the same time.

      On a positive note for me my first drive successfully installed. Going to start the other addition later tonight when others are sleeping. They get testy when I shut off the tv server lol.
    • RobertR728 wrote:

      Now I understand why you all said it thrashes the drives...
      And if your drives had significant age on them the chances of a drive failure, during a rebuild, are significant. Along those lines, don't forget to backup your irreplaceable data. Drive failure is not a matter of "if", it's a matter of "when".
      _____________________________________________________________________

      I'll say it now that it won't jinx anything - I hope your avatar is not an x-ray of your hand. :)
      Good backup takes the "drama" out of computing
      ____________________________________
      OMV 3.0.99 Erasmus
      ThinkServer TS140, 12GB ECC / 32GB USB3.0
      4TB SG+4TB TS ZFS mirror/ 3TB TS

      OMV 3.0.99 Erasmus - Rsync'ed Backup
      R-PI 2 $29 / 16GB SD Card $8 / Real Time Clock $1.86
      4TB WD My Passport $119
    • So that has me wondering another question. I used the software raid built into OMV.
      I've read that snap raid plug-in if an array fails the disks could still be read one by one to recover allot of the data.
      Does that same effect happen with OMV built in software raid? Meaning if there is an array fail without using snap raid can the data be read using say a Linux boot disk?

      Oh and yes my avatar is my left wrist after a dirt bike crash. I was probably 30 and invincible. Lol but not so smart sometimes.

      Thanks :)
      Robert
    • Regarding software or hardware RAID recovery, the answer to what I think you're asking is "no". If you're doing mdadm (software) RAID 5, data and parity is striped across all disks. Parity information will rebuild data from 1 drive failure but more than that and the array is finished. Is forensic recovery of "some" data from a RAID5 array possible? Yes. But it's not possible in any practical sense and certainly not something that the average user could do at home without some sort of expensive recovery utility / service (results would vary). It's much easier and far better to have backup.

      SnapRAID and software (mdadm) RAID are two very different things, that do not work together.

      Snapraid, as I understand it (I don't use it) is closer to something that could be called backup. It can recovery an individual disk among a collection of disks and individual files after deleting them. You'd also get bitrot protection (from silent errors) which is something software RAID doesn't provide. Some of the more experienced users on this forum are using it and like it. It seems to be pretty popular. As you're aware, OMV offers it as a plugin. Information on what it is and how to implement it can be found here. SnapRAID.
      _______________________________

      All I can say on that x-ray is, man "that must have hurt!" Yeah, in our youth we seem to be ignore a simple fact; we get one (1) body and we have to live with it the rest of our lives. I took horrendous chances myself, but I got real lucky. I could very easily have been in a wheelchair.
      Good backup takes the "drama" out of computing
      ____________________________________
      OMV 3.0.99 Erasmus
      ThinkServer TS140, 12GB ECC / 32GB USB3.0
      4TB SG+4TB TS ZFS mirror/ 3TB TS

      OMV 3.0.99 Erasmus - Rsync'ed Backup
      R-PI 2 $29 / 16GB SD Card $8 / Real Time Clock $1.86
      4TB WD My Passport $119
    • I thought i was implementing Snapraid when i first built the array. That's how dumb i was to what i was doing. I figured it out that i didn't get what i really wanted that Snapraid offers. I will read up on it.

      The wrist didn't hurt when it happened but an hour later was hell. I begged them to put me to sleep and gave my wife all authority to make any decisions about my wrists. They bent it back and sent me to a different surgeon a week later. I spent that week in the hospital and don't remember much of it at all. I am feeling my youth and the one body rule as i get older. I sometimes think i can do more than i actually can lol
    • Raid 5 growing

      Adding a drive to a raid 5 array means rewriting absolutely everything on the existing drives. I know you wanted the added space, but you really beat the original drives up pretty hard. Might want to think about adding a hot spare or two now.

      As for broken bones, I've had a few. I'm going on 56 now and 15 years ago I had a low speed motorcycle accident. I broke my finger, clavicle (sternum end, pretty rare), a pile of ribs and crushed my T7 vertebrae. Soft tissue injuries included a bone deep cut above my eye and nearly the complete severing of my ear and many more pulls and tears. Fortunately a plastic surgeon was available to fix my ear and they assigned a "sports doctor" to rehab me. That guy is completely merciless and has no soul, but I'm glad now that he made me "walk it off" and "work it out". If you met me, you'd never know any of that happened. But hey, I walked away and was going to ride my bike home, but it wasn't up to it. Adrenaline is like that.

      Sent from my Moto G (4) using Tapatalk