OMV 3.X versus OMV 2.X; "Growing" a RAID 5 array

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    • OMV 3.X versus OMV 2.X; "Growing" a RAID 5 array

      (Per a forum user conversation in another thread) Grow RAID 5

      After testing RAID 5 scenarios in VM's of OMV 3.0.73, versus a real world platform running OMV 2.1:
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      It seems that the behavior of the "Grow" button in <System>, <RAID Management> has changed between OMV versions 2.X and 3.X.

      Where the "Grow" button in OMV 2.1 triggers an array restrip operation that integrates a new drive, the "Grow" button in 3.X versions simply adds a drive to the array as a hot spare which is more in line with the mdadm --add command line.

      To integrate a disk into an OMV 3.x array (Grow it) it was necessary to do it from the command line (as follows).
      mdadm --grow /dev/md0 --raid-devices=4


      Perhaps there's a reason for the change?
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      If restriping (or Growing) a RAID 5 array is to be supported in OMV 3.X , it makes sense to attach the CLI operation (mdadm --grow /dev/md0 --raid-devices=4) to the Grow button in RAID Management.
      Similarly, when adding a hot spare to an array, it would be more intuitive if a new GUI "Add" button is attached the CLI operation (mdadm --add /dev/md0 /dev/sde).

      Are we off base or are we missing something? In any case, any information or an explanation would be appreciated.


      Thanks

      Video Guides :!: New User Guide :!: Docker Guides :!: Pi-hole in Docker
      Good backup takes the "drama" out of computing.
      ____________________________________
      Primary: OMV 3.0.99, ThinkServer TS140, 12GB ECC, 32GB USB boot, 4TB+4TB zmirror, 3TB client backup.
      OMV 4.1.13, Intel Server SC5650HCBRP, 32GB ECC, 16GB USB boot, UnionFS+SNAPRAID
      Backup: OMV 4.1.9, Acer RC-111, 4GB, 32GB USB boot, 3TB+3TB zmirror, 4TB Rsync'ed disk
    • It's still outstanding but I've come to understand why. When it comes to growing an mdadm RAID array, users tend to "click" without contemplating the consequences and get in over their heads. Then, with a dead or dying array (usually without backup), they return to the forum after compounding the problem. Often, it's unsolvable.

      If you want to grow your array, you can find the command lines to do it here. - > mdadm RAID 5 - 3 disks to 4 disks

      If something goes wrong (that's not critical), here's a resource to recover your array.
      Recover array (There's good general reading at this site.)

      _______________________________________________________

      With the above noted - if you don't have a full backup of all the contents on your array, or at least the data that you can't afford to lose, don't try to grow it. Arrays die in these processes all the time. You can search this forum and others for more than a few examples.

      Video Guides :!: New User Guide :!: Docker Guides :!: Pi-hole in Docker
      Good backup takes the "drama" out of computing.
      ____________________________________
      Primary: OMV 3.0.99, ThinkServer TS140, 12GB ECC, 32GB USB boot, 4TB+4TB zmirror, 3TB client backup.
      OMV 4.1.13, Intel Server SC5650HCBRP, 32GB ECC, 16GB USB boot, UnionFS+SNAPRAID
      Backup: OMV 4.1.9, Acer RC-111, 4GB, 32GB USB boot, 3TB+3TB zmirror, 4TB Rsync'ed disk
    • flmaxey wrote:

      It's still outstanding but I've come to understand why. When it comes to growing an mdadm RAID array, users tend to "click" without contemplating the consequences and get in over their heads. Then, with a dead or dying array (usually without backup), they return to the forum after compounding the problem. Often, it's unsolvable.

      If you want to grow your array, you can find the command lines to do it here. - > mdadm RAID 5 - 3 disks to 4 disks

      If something goes wrong (that's not critical), here's a resource to recover your array.
      Recover array (There's good general reading at this site.)

      _______________________________________________________

      With the above noted - if you don't have a full backup of all the contents on your array, or at least the data that you can't afford to lose, don't try to grow it. Arrays die in these processes all the time. You can search this forum and others for more than a few examples.
      Thanks for taking the time to reply, appreciated.

      Yes I've already manually got my RAID array reshaping in the background (additional 6Gb disk = couple of days likely!), just wanted to see whether or not this was a bug as, like other posters, I've done this several times before all in the GUI. Makes sense what you said and no drama to revert to the command line - fingers crossed my additional storage will satisfy me for a while (as additional storage at this sort of size starts to get expensive!).

      Thanks again.
    • Here's to hoping nothing goes south during the reshape. (It's not over until it's over.) If it comes out alright, as a last step you'll have to go into Storage, File Systems and "Resize" your file system to use the additional space.
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      If adding a 6TB disk, I'm guessing you have a sizeable array. In any case, give some thought to backup even if that would mean backing up individual shared folders to an external drive or host. (They're making reasonably priced 8TB externals these days.)

      Keep in mind - the more disks you put into the array AND, as the existing drives grow older, the probabilities of a catastrophic failure increase. Just a thought, not a sermon. :)

      Video Guides :!: New User Guide :!: Docker Guides :!: Pi-hole in Docker
      Good backup takes the "drama" out of computing.
      ____________________________________
      Primary: OMV 3.0.99, ThinkServer TS140, 12GB ECC, 32GB USB boot, 4TB+4TB zmirror, 3TB client backup.
      OMV 4.1.13, Intel Server SC5650HCBRP, 32GB ECC, 16GB USB boot, UnionFS+SNAPRAID
      Backup: OMV 4.1.9, Acer RC-111, 4GB, 32GB USB boot, 3TB+3TB zmirror, 4TB Rsync'ed disk
    • bvrulez wrote:

      I could never find any instruction on how to grow my RAID5 via GUI.
      Did you search the forum? Normally, adding the disk and clicking grow in the raid tab and resize in the filesystems tab is all that is needed.
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    • I did it manually several times in the console. Clicking grow did not add the disk. I had this issue the last time, also, I think. This time, I first put a filesystem on the disk and shared it via samba to check the disk (it had SMART status red and I wanted to re-allocate all broken sectors fist - this worked, SMART is green now, no pending sectors and no errors.)

      So, mayby I did not free this disk enough to make it addable to the RAID. But I did try to unmount it and delete the filesystem. But every time I want to add a disk I have troubles with it in the GUI because it is not that clear what to do. Or, when clicking on "grow" and nothing happens, there is no indication if this step should be possible or what could be the issue.

      EDIT: I searched google which brings up the forum a lot of times.

      The post was edited 1 time, last by bvrulez ().

    • bvrulez wrote:

      Or, when clicking on "grow" and nothing happens, there is no indication if this step should be possible or what could be the issue.
      If you are putting a filesystem on the disk first, that is a problem. You should be wiping the disk if there is anything on it. Most new disks come clean so this step isn't necessary. And when you grow an array, a dialog will pop to ask you which disk(s) to add. if you didn't see this, you didn't have disks available (probably because it had a filesystem on it) and it definitely did not grow your array. While I think the documentation could be better, I really don't think most users need raid.
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    • Thanks for the clarification. Yes, most of my HDDs are used. What kind of "wiping" would be sufficient? Because I also tried to unmount the disk, delete the filesystem and then still the disk was not available to the RAID. Maybe a restart would have made a difference?

      Also, thanks for talking about RAID. This is a bit off topic, but I want to explain why a RAID is a good thing in my eyes: I got me openmediavault because I was planning to have a RAID. I am using my RAID6 (I misspelled it earlier) without any backup. This is just for movies. Some of them I still have on DVD/Bluray. So, my RAID gives me a first wall of security against hardware failure. Backing everything up would cost > 300 Euros at the moment. Bying the movies again would maybe cost tripple the amount. But regarding the error rate it is probably better without backup over all from a cost perspective. Since the backup in case of movies is on all the circulating dvds/bluerays.
    • bvrulez wrote:

      What kind of "wiping" would be sufficient?
      Quick wipe from the physical devices tab should be fine.

      bvrulez wrote:

      Because I also tried to unmount the disk, delete the filesystem and then still the disk was not available to the RAID. Maybe a restart would have made a difference?
      Nope. It needs to be wiped.

      bvrulez wrote:

      Also, thanks for talking about RAID. This is a bit off topic, but I want to explain why a RAID is a good thing in my eyes: I got me openmediavault because I was planning to have a RAID. I am using my RAID6 (I misspelled it earlier) without any backup. This is just for movies. Some of them I still have on DVD/Bluray. So, my RAID gives me a first wall of security against hardware failure. Backing everything up would cost > 300 Euros at the moment. Bying the movies again would maybe cost tripple the amount. But regarding the error rate it is probably better without backup over all from a cost perspective. Since the backup in case of movies is on all the circulating dvds/bluerays.
      I don't think raid is giving you what you think you are getting. yes, it is protecting you from a failed drive but not from an accidental delete or corruption or crypto virus, etc. Personally, I think you would be better off to use unionfilesystems to pool the disks and snapraid with one or two parity disks. Either way, backup should be a priority instead of extra parity disks that are only giving you redundancy.
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    • bvrulez wrote:

      Is there a way to transfer easily from a RAID to SnapRaid? Can you recommend a guide?
      Nope. You need to wipe your disks and format them with a filesystem, mount them in the filesystems tab, and then restore your data from backup. There is no guide for this because there are too many unique setups to try and account for.
      omv 4.1.17 arrakis | 64 bit | 4.15 proxmox kernel | omvextrasorg 4.1.13
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      Please read this before posting a question and this and this for docker questions.
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