if RAID and ZFS is not backup, So why we use NAS ?

  • I found it on every blog that RAID and ZFS is not a Backup . so what we do with NAS and where do we save backup ?
    I was taking backup in my WD 4tb external HDD i have 3. some how 1 drive got corrupt and i lost my 4 TB data . so I am thinking build a NAS with 4x6TB Drive with RAIDZ1. Can i have some suggestion . I am currently testing OMV 3.0 with ZFS .. with 3x500GB HDD.

  • NAS is not a backup device itself and I think this is what you need to understand. It is a way to have available files on the network from a centralized point with a centralized management. If a NAS device will have RAID etc for speed/high availability etc. it is a different story. There are NAS devices with one drive.

  • ZFS/RAID is not a Backup is refer to those user that only have one copy of his valuables files on raid/zfs. and because this filesystem have redundant info thinks that his data is safe, and forgot that, not only one disk can fail.

    If you have your valuable data on your home PC and have a copy on your NAS, you have 2 copies of your files in 2 physical independent machines, so in this case, yes, is a backup.

    PD: you can have only one copy of files in your NAS (like video, series, mp3, that are easy for you to re-donwload in case of fail) and backup copy of your valuable data ( personal photos, wedding video, etc...)

  • Problem is synchronization or mirroring. If you delete a file on your souce after some time it will be also deleted on your synched devices.

    You can consider your NAS as a first level backup for your data on your laptop. But if the data are only available on the NAS a RAID does not help you in case you delete one file.

    One step better solution is using snapshots. By this you are creating different versions of the files. And even if you delete a file you can find the file in previous snapshots.

    Then, to have a better backup strategy, you should store data on an device independent from your NAS. For example an USB-drive you remove from the NAS when not used. This can protect you from virus or surges over the power network.

    Another improvement would be a remote backup on a NAS at your friends house or in the cloud. This protects your data even from local "disaster" (e.g. flood, fire, burglary).

    For further reading ask google for "backup strategy".
    Here is a starting point https://www.backblaze.com/blog/the-3-2-1-backup-strategy/

  • Let's use an analogy.

    Believe it or not, I've seen high security armored cars with two separate batteries, two alternators and two electronic ignition systems. The idea is, if one fails (one battery, one alternator or one ignition system), the other still works. But does the car, as a whole, have back up? The answer is no. The car's purpose is transportation. If it runs off the road, is in an serious accident, etc., etc., there's no more "transportation". For true backup, you'd need another car. (Which, while off topic, is done with a lead and chase vehicle.)

    The above analogy applies to your NAS as well. If you "wreak" your NAS (the mobo slowly dies while corrupting your hard drives, the power supply fails badly and fries your drives, a virus gets out of hand, etc., etc.), without backup, your data is gone. Note that RAID in any flavor (Hardware adapter / ZFS / mdadm / BTRFS) will not protect your data from anything previously mentioned.

    As suggested above, an independent device that duplicates the important data on your NAS represents basic backup.

    That could be:
    - An external USB drive and a replication event, at a regular time intervals (there's lots of ways to do this). To guard against potential power problems, after replicating, I'd turn it off.
    - A client on your LAN with a big hard drive that duplicates your NAS' data.
    - An independent dedicated device that copies your data at regular intervals. (Includes off loaded ZFS snapshots.)

    In my case, I duplicate all data to 3 different devices at varying time intervals from 1 day, 1 week, to a few months. That might seem to be extreme but it has served me well.

    If you already have a configured NAS, backing it up doesn't have to be expensive. Really, it's a matter of sufficient hard drive space for the second copy.

  • this is how I treat RAID1 and backups:
    - Do you care about your data, but not so much? Raid1 is fine, your data is safe against most hardware problems, still weak against every tipe of software problem. You still risk to lose your data (deleted files,power supply fry both hdds at the same time,ecc.). If you are fine with that, RAID1 is still a good way to secure your data
    PRO: once you build the RAID1, you will never have to spend time on it again
    CONS: you still risk to lose your data

    - You absolutely don't want to lose your data? Go for a RAID1 + External hdd. For everything like photos and documents I keep them on my RAID1, and every once in a while i backup them on an external hdd
    PRO: if your house won't burn the risk of lose your data is nearly 0
    Cons: you need to spend time on it every time you want to backup your data

    Intel G4400 - Asrock H170M Pro4S - 8GB ram - Be Quiet Pure Power 11 400 CM - Nanoxia Deep Silence 4 - 6TB Seagate Ironwolf - RAIDZ1 3x10TB WD - OMV 5 - Proxmox Kernel

  • RAID1 is still a good way to secure your data

    RAID1 provides zero data protection -- it's only about availability. It's just the try to retain data accessible in a 'one single disk failed hard' situation and how good that works you see yourself (you're the one now with 3 identical threads complaining that your RAID1 always disappears after a reboot).

    RAID1 also has not the slightest abilities to provide data integrity so anybody who loves his data should stay away from RAID1 (it's a concept from last century when we didn't had better alternatives for server boot disks).

    A zmirror or a btrfs RAID1 are way better alternatives since both provide data integrity combined with self healing, you can do periodic snapshots for data protection and to increase the protection level easily send them to another disk/location so they're physically separated (the commands are similar: zfs send/receive and btrfs send/receive. With a zmirror using znapzend to create/transfer/delete snapshots is really easy. And the remote target can be an ARM based mini NAS running OMV/ZFS so there's really no need to physically connect/disconnect HDDs for backup purposes. Simply use a small ARM board + HDD in another room/location)

  • Hi guys.
    I ran a search on the forum for Backblaze and I ended up in this topic.
    I am seriously considering buying 3x 2TB hdds and use them in OMV with snapraid and possibly mergefs.
    But right now I'm not very worried about my storage choices, I am more worried about my backup choices.
    Since Crashplan is no longer financially viable for me, I'd like my NAS to backup to a Backblaze B2 bucket.
    How can I backup to backblaze? Duplicity (I meant Duplicati)? Are there any other options instead of Duplicati? Maybe Rclone?

  • There is a Duplicati plug-in.
    Many users of Duplicati perform their backup at Backblaze B2


    Indeed, when I wrote duplicity in my previous message I actually meant duplicati.
    So my question is if there are other alternatives to duplicati. And the reason is simple: I tried installing duplicati on a OMV 3 test VM and it failed miserably on me. So I would either need help with installing duplicati or some advise on alternatives.
    Thanks in advance.

  • Did you find any alternative?

    No, I didn't. In fact it's a whole lot worse than that. Because of that I stopped my whole NAS project and 2 months ago I almost lost a significant part of my photos due to hdd issues.
    I have just recovered from that and I am currently looking into alternatives.

    Duplicati seems nice but it needs .Net/Mono, which is IMO a big load of crap and the truth is I never made it to get going.

    To me, Snapraid+MergerFS+some_backup_scheme+Rclone would seem to me the most viable way of doing what I want.
    But I don't know any backup_scheme that would allow me to maybe automatically Tar files, encrypt them with GnuPG, upload to Backblaze B2 bucket using Rclone and write a log of the outcome and register in which Tar the files are, you know, so that later I can easily run a search on it and simply download the needed Tar's in case something "goes south".

    Anyone experienced enough could give us a hand here? Thanks in advance.

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