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Cake day: July 5th, 2023

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  • With 2 disks that would be type mirror in ZFS-speak, completely built-in. Equivalent to RAID1 in terms of hardware fault tolerance.

    You could do a 3-disk mirror or n-disk mirror really. The RAID5/6 rough equivalents are called RAIDzN where N is the number of disk failures they tolerate. E g. RAIDz1, RAIDz2, etc. You probably want a mirror unless you need more space than a single disk provides.


  • Yup, turn it on, let it do a scrub, then turn it off. I’d still use redudnancy though. Not merely to cover the case of the drive failing, but also to cover the bit rot use case. It’s exceedingly unlikely bits to rot at the exact same spot on two or more disks. When ZFS finds a checksum mismatch during a scrub (which indicates bit rot), it’ll be able to trivially recover the data from the drive where the checksum matches. It’ll then rewrite the rotten part.



  • ZFS with automatic snapshots and scrubbing. This will keep as many and as old snapshots as your like. It’ll ensure the files don’t rot. It’ll ensure the media doesn’t die, so long as you have enough redundancy and you replace disks as they die. This is what I’d trust for long term storage because I think I understand how and why it works. It should last as long as I feed it disks. If I delete something, I should be able to restore it from a snapshot. The hardware doesn’t need to be anything fancy. Just a Pi 4/5 with a couple of WD Elements would be fine. Could add more disks for more redudnancy. I’m running 2-disk residency.

    You don’t have to touch the software if it’s not exposed to the Internet. Whatever works today on it will work 20 years from now, so long as the hardware works. A couple of spare Pis, SD cards and power supplies should let it last for decades.