Add Second Disk - Create RAID

  • Can I add a second drive (clean) to this hard drive and create a RAID?

    ???


    And the reason would be because...????


    Do you even know what RAID is for?

  • Yes.

    RAID 1 - Duplicated or mirrored disk array

    You still haven't answered the main question: what is the reason to have a RAID1 ?

    If you want to have a full disk copy of your DATA on "disk1" to "disk2", just mount "disk2" on OMV and run a scheduled job (every x time depending on the amount of writing/increase of volume DATA) as simple as rsync -a /path-to-disk1/ /path-to-disk2/


    If you go with RAID1 option, you need to be prepared to accept the fact that, if things go wrong, you will have a big headache trying to salvage it: meaning you need to know commands on how to recover from it. (Sorry but you don't seem to know)


    NOT only that but in order to create the RAID, you need to WIPE the drive prior to CREATE, which implies the format of the drive with the DATA.


    As, as the RAID Guru geaves say, "RAID is not a backup"


    If you still insist in a RAID1 solution with DATA already existant: you can try with BTRFS or ZFS but you still need to convert the DATA drive to that filesystem and then, make the RAID1 via command line.
    I won't post any links because I don't want to be held accountable if you loose your DATA trying any things I show but, google is your friend if you decide to go this route.

    Good luck

    • Official Post

    Soma I'm pleased you answered this :) I read the initial post when it was posted and thought then 'that is a serious PIA and not for the faint hearted'


    So to answer leonovo in a single word -> No, not unless you have experience of raid configuration and their behaviour, Soma suggestion to use rsync is just as good and simpler to use.

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


    OMV 6x amd64 running on an HP N54L Microserver

  • You still haven't answered the main question: what is the reason to have a RAID1 ?

    If you want to have a full disk copy of your DATA on "disk1" to "disk2", just mount "disk2" on OMV and run a scheduled job (every x time depending on the amount of writing/increase of volume DATA) as simple as rsync -a /path-to-disk1/ /path-to-disk2/

    This is a nonsense for me.

    If you have a rsync's copy of a whole disk and the main disk fail, all services like, for example, docker's containers, will go down cause the path will not be reachable anymore.

    With a RAID1 config the "/srv/dev-disk-by-uuid/" is the same for the 2 disks, 'cause they will merge in a "unique device" so, if one of them fail, the system stays up.

    Yes, if something goes wrong the error will replicate throught the 2 disks, but backups are here for a reason.

  • This is a nonsense for me.

    That is why all people are different. Each one of us have a different perspective of things, ;)


    If you have a rsync's copy of a whole disk and the main disk fail, all services like, for example, docker's containers, will go down cause the path will not be reachable anymore.

    Then, just edit the docker paths to point to the new path and relaunch the containers.

    Only downtime you'll have is between the awareness of the containers beeing down and till you edit the paths to reflect the new location.


    With a RAID1 config the "/srv/dev-disk-by-uuid/" is the same for the 2 disks, 'cause they will merge in a "unique device" so, if one of them fail, the system stays up.

    Yes, RAID is about availability. But I'm pretty sure that you know that comes with costs.
    On this particular discussion, you would have the RAID mounted as degraded and you would still have everything running.

    Is this really mandatory for a personal NAS?

    Does it pay off having RAID (and the learning curve that most don't take until they have problems) just to have a home server for pics/movies/tvshows?

    And even after having problems, most just finally realize they don't have backups because they assume (wrongly) that the DATA is in several disks so, it must be replicated and each disk can be used individually after one broke.

    Yes, if something goes wrong the error will replicate throught the 2 disks, but backups are here for a reason.

    And with this, you'll need 3 disks instead of 2 for a RAID1 (waist of resources, sorry):

    2 disks on the RAID1 with xTB plus (at least 1) with the same xTB for a backup when you can have only 1 disk xTB with the 2nd one beeing the rsynced.

    This is just my personal opinion and an aftermath of seeing too many forum posts on people with RAID issues without having backups nor knowing how to deal with RAID command line until it was too late and DATA was lost.


    Take it with a pinch of salt. especially since I DO use a RAID1 (on BTRFS) for my Nextcloud instance. Only because at the time I also didn't know nothing about RAIDs and whatnots.

    Nonetheless, I also have a secondary backup to the RAID on an extra disk that, when the time comes will become the main DATA drive and I'll get rid of the BTRFS RAID (and regain an extra disk in the mean time)

    • Official Post

    With a RAID1 config the "/srv/dev-disk-by-uuid/" is the same for the 2 disks, 'cause they will merge in a "unique device" so, if one of them fail, the system stays up.

    Is the rest of your system highly available (ie dedundant power supplies, network, etc)? Most people running OMV do not have anything else redundant making raid less useful. And most OMV users can tolerate a little downtime to restore from backup. We actually see more people have downtime due to raid assembly problems than we do people have their non-raid disk fail and have to restore from backup.

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  • Yes

    Sorry for the delay but this thread fell down on the notifications list.

    Did you managed to work out a solution to what you wanted?

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