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I'm planning to do redundancy backup for my office server running Ubuntu 14 and the ZFS option came up in my research. To my understanding, hardware raid (RAID1) creates a full clone (mirror) of my disk on another disk, therefore having two exact copies running. If one fails I can just swap the failed disk and it will just rebuild another copy to the new disk. Can I set up the same function with ZFS?

From what I've read, I'm not so sure that the OS is part of the created zpool. What if the disk fails with the OS in it?

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  • Yes: ZFS calls it RAID-Z1, RAID-Z2 and RAID-Z3 (those are similar to RAID-5 (allows for 1 disk failing), 6 (same for 2 disks) and 7 (same for 3 disks )) and "Striped Vdev’s" (= RAID-0/mirroring what you are asking about) . If you plan to use 5+ Tb disks rebuilding can take weeks ;) Oh, and RAID is not a replacement for a backup (the title would assume you think that that is the case).
    – Rinzwind
    Feb 21, 2018 at 9:40
  • Thanks for that answer. Any installation links i could try for this setup?
    – airzoink
    Feb 21, 2018 at 9:48
  • Guess why I did not make it an answer? No, I do not. That was all I know about ZFS because we once had a discussion about it for our internal machines but we opted for cloud servers :-D
    – Rinzwind
    Feb 21, 2018 at 9:52

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First: RAID is not backup. It gives disk redundancy, so if a disk dies you can replace it without loosing data. If you delete a file it will be gone on all copies on disk. So, raid for handling disk issues, backup for handling corrupted or removed files.

That said, ZFS (and similar filesystems) have features like snapshot and clones that can act as (a part of) a backup solution. ZFS uses CopyOnWrite, so a snapshot don't take up any space before you start modifying the original filesystem. This is great for having online access to "yesterdays" copy - but to be safe, we also need a backup "off premise" in case of a catastrophic event where you loose the whole server - fire, theft or so.

As far as I remember Ubuntu can be set up to boot from ZFS too, but I havent tried it. Originally (on Solaris whare ZFS was born) it required a seperate Zpool - only mirrored - for root file system and one (or more) Zpool for other disks. But that might be different on Linux.

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  • Yes, i think redundancy is the right word for what i am looking for. I'm already backed-up in the cloud. Thank you for your answer.
    – airzoink
    Feb 22, 2018 at 3:57

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