Start off with one disk, add second disk later and create mirrored / RAID 1 array, is this possible?

  • Hi, I'm looking to purchase an Odroid HC4 and run OMV on it. Due to budget constraints I want to start off with a single 6TB HDD and probably add a second 6TB HDD a few months down the line. I want this second HDD to be a mirror of the first HDD and have them both eventually set up in a RAID 1 array.


    Is this possible in OMV without having to wipe all data on the first HDD and having to create a completely new RAID 1 array from scratch?

    I know several NAS manufacturers do in fact offer this feature but I haven't found much info on whether or not this is actually possible in OMV.

    Anyway, thanks in advance. I'll be looking forward to your responses.

  • Is this possible in OMV without having to wipe all data on the first HDD and having to create a completely new RAID 1 array from scratch?

    No, it is not possible.


    Most people here would not suggest to use RAID1. Instead use your first drive as primary drive and then using rsync to sync the data from the primary drive to the second drive which would become your backup drive. Even better is to use rsnapshot instead of rsync. That way you even have a versioned backup. Thus you can go back in time and restore previous versions of the drive.

    If you add off-site backup you have a pretty solid backup strategy.


    My thoughts about... RAID

    https://blog.storagecraft.com/5-reasons-raid-not-backup/

  • No, it is not possible.

    Thanks for clearing that up! :)


    Sorry for being a n00b, but if I were to use rsync or rsnapshot in such a setup and my primary drive were to fail, would I then still be able to instantly access my data? I assume the backup drive would be accessible through its own drive path?

    If I were to replace the primary drive, I take it I would have to rebuild the primary drive from the backup drive, correct? Would I still be able to access my files during this process?

    Thanks in advance.

  • I assume the backup drive would be accessible through its own drive path?

    Yes


    If I were to replace the primary drive, I take it I would have to rebuild the primary drive from the backup drive, correct? Would I still be able to access my files during this process?

    Yes, but on the backup drive. You have to create shared folders to the relevant folders on the backup drive and add them to the service you are using to access your data.

  • Thanks, I think I understand. If my primary drive were to fail, I would have to redirect any services I were using (coreElec, piCorePlayer, etc ) to the backup drive.

    Just out of curiosity, what would be the argument for people to recommend such a setup over a RAID 1 setup? Since in RAID 1 there is never the necessity redirect anything when a drive fails?

    Thanks

  • Is a backup more secure than a mirrored disk? how so?

    A mirror is not a backup, it's a mirror.


    You have File A that is super important.. you or someone else accidentally deletes File A... File A is then deleted on both drives. That's not a backup, it is a mirror


    A Backup, File A gets deleted, and a copy is stored at another location/on another drive, thus making it easy to restore.


    That's as simple as I can make it.

    Air Conditioners are a lot like PC's... They work great until you open Windows.


  • Did you read the article I linked?


    If you saved a file with a modification you don't like it is instantly saved on the mirror.

    If you delete a file by accident it is instantly gone on the mirror.

    If you share gets encrypted by malware it is instantly encrypted on your mirror.


    Nothing of this happens if you have a versioned backup like if you use rsnapshot.

    If you use rsync it will still happen, but only after the next run of rsync.

  • Since in RAID 1 there is never the necessity redirect anything when a drive fails?

    Your argument here is about availability, yes if a drive fails within that mirror then the mirror is still 'usable' but your still looking at performance degradation particularly when the mirror is being rebuilt and leaving the raid to rebuild without accessing it is a better option.


    If you want to use a Raid setup at least ensure you have a backup!!

    Raid is not a backup! Would you go skydiving without a parachute?

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