Hardware RAID1 and system+data on a single drive for easy maintanence?

  • For the past three years I've been using a QNAP TS-251+ as a simple NAS and Plex server. I wanted this to be a no-fuss machine, but two things made me question RAID and QNAP.


    First, when I decided I wanted to move to different drives, I hoped RAID1 meant that I could replace one HDD, let it replicate, then replace the second, and let it replicate. Sadly not! I ran into difficulties and had to recreate my data disks from scratch. Second, the QNAP interface was complex and I didn't like that the bi-monthly system updates required a firmware flash. After three years, it finally hung during a firmware update and is now unusable.


    Even though I don't want to mess with computers anymore, I decided to build my own using OpenMediaVault, which I really like the looks of (thank you for making it!). I've purchased a system in which I can place my two 2.5 inch SSD's using hardware RAID1; it also has a slot for an mSATA. I'd like to have the system and data on a single disc, in two partitions. If one disc dies, I can continue on as I replace the dead one with no fuss. I can stick a small mSATA disc as the system disk, but that means I have to back that up separately as well, right?
    It looks like NAS types of systems, and Open Media Default specifically, want there to be a separate system disk. Is it unrealistic to want system and data on a single disk that is mirrored and easily replaced? I'd rather not have to backup the system partition and data discs separately. I'm not committed to RAID, I simply want an automatic bootable mirror. Suggestions?

    • Offizieller Beitrag

    There are many threads in the forum about the sense and non-sense of RAID. Especially when it comes to RAID1. Search the forum for "RAID is not backup".


    One example: My thoughts about... RAID


    One feature of a RAID1 is that data are instantly written to both drives. So also mistakes are written instantly. In case of a OS in RAID1 this means, if something goes wrong during an installation or upgrade, your RAID1 is worthless. You would be better of with a backup.


    Additional issue with hardware RAID: What do you do if the hardware has a problem? Basically you need a backup for the hardware as well.



    Even though I don't want to mess with computers anymore

    Then keep it simple. No RAID. Especially no hardware RAID. Use one disk as primary storage and setup a rsync or rsnapshot job to backup the data from the primary disk to the backup disk in regular intervals.
    If your system can boot from the USB port you can install the system on USB. Then it is really easy to make clones of the system drive.

  • Thanks for the response! Is there anything that would let me make a bootable clone without having to take the system down? I don't care about mistakenly deleted files, snapshots, etc. When a disk fails, I want to fall-back to clone, replace fail, restore, and go. (When I used to use Linux as my desktop, there wasn't, and I've gotten used to Carbon Copy Cloner on MacOS.)


    Also, I wonder why is OMV biased toward a separate systems disk?

    • Offizieller Beitrag

    Is there anything that would let me make a bootable clone without having to take the system down?

    There is a backup plugin which uses rsync, dd or fsarchiver to backup the live OS, but it will not give you a bootable disk. You will have to do a restore, which you should test as it is not too simple.

    • Offizieller Beitrag

    The main merit is separation.


    The NAS will keep working even if one or more data storage drives fail or becomes full. And you can use the operating system to diagnose and possibly fix the problem.


    In OMV the operating system is very small and will typically be fully cached in RAM. And there is a plugin that radically reduce writes to the root filesystem. So you can without problems have the operating system on a USB flash drive or a SD card. It can even be recommended! This free up a SATA port for another big data storage drive.


    Having the operating system on a small removable flash memory also makes it very fast and easy to clone.

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