I’m working on a project to back up my family photos from TrueNas to Blu-Ray disks. I have other, more traditional backups based on restic and zfs send/receive, but I don’t like the fact that I could delete every copy using only the mouse and keyboard from my main PC. I want something that can’t be ransomwared and that I can’t screw up once created.

The dataset is currently about 2TB, and we’re adding about 200GB per year. It’s a lot of disks, but manageably so. I’ve purchased good quality 50GB blank disks and a burner, as well as a nice box and some silica gel packs to keep them cool, dark, dry, and generally protected. I’ll be making one big initial backup, and then I’ll run incremental backups ~monthly to capture new photos and edits to existing ones, at which time I’ll also spot-check a disk or two for read errors using DVDisaster. I’m hoping to get 10 years out of this arrangement, though longer is of course better.

I’ve got most of the pieces worked out, but the last big question I need to answer is which software I will actually use to create the archive files. I’ve narrowed it down to two options: dar and bog-standard gnu tar. Both can create multipart, incremental backups, which is the core capability I need.

Dar Advantages (that I care about):

  • This is exactly what it’s designed to do.
  • It can detect and tolerate data corruption. (I’ll be adding ECC data to the disks using DVDisaster, but defense in depth is nice.)
  • More robust file change detection, it appears to be hash based?
  • It allows me to create a database I can use to locate and restore individual files without searching through many disks.

Dar disadvantages:

  • It appears to be a pretty obscure, generally inactive project. The documentation looks straight out of the early 2000s and it doesn’t have https. I worry it will go offline, or I’ll run into some weird bug that ruins the show.
  • Doesn’t detect renames. Will back up a whole new copy. (Problematic if I get to reorganizing)
  • I can’t find a maintained GUI project for it, and my wife ain’t about to learn a CLI. Would be nice if I’m not the only person in the world who could get photos off of these disks.

Tar Advantages (that I care about):

  • battle-tested, reliable, not going anywhere
  • It’s already installed on every single linux & mac PC , and it’s trivial to put on a windows pc.
  • Correctly detects renames, does not create new copies.
  • There are maintained GUIs available; non-nerds may be able to access

Tar disadvantages:

  • I don’t see an easy way to locate individual files, beyond grepping through snar metadata files (that aren’t really meant for that).
  • The file change detection logic makes me nervous - it appears to be based on modification time and inode numbers. The photos are in a ZFS dataset on truenas, mounted on my local machine via SMB. I don’t even know what an inode number is, how can I be sure that they won’t change somehow? Am I stuck with this exact NAS setup until I’m ready to make a whole new base backup? This many blu-rays aren’t cheap and burning them will take awhile, I don’t want to do it unnecessarily.

I’m genuinely conflicted, but I’m leaning towards dar. Does anyone else have any experience with this sort of thing? Is there another option I’m missing? Any input is greatly appreciated!

  • 𝕽𝖚𝖆𝖎𝖉𝖍𝖗𝖎𝖌𝖍@midwest.socialEnglish
    2·
    11 hours ago

    It’d be more space efficient to store a COW2 of Linux with a minimum desktop and basically only DarkTable on it. The VM format hasn’t changed in decades.

    Shoot. A bootable disc containing Linux and the software you need to access the images, and on a separate track, a COW2 image of the same, and on a third, just DarkTable. Best case, you pop in the drive & run DarkTable. Or, you fire up a VM with the images. Worst case, boot into linux. This may be the way I go, although - again - the source images are the important part.

    I’d be careful with using SSDs for long term, offline storage.

    What I meant was, keep the master sidecar on SSD for regular use, and back it up occasionally to a RW disc. Probably with a simply cp -r to a directory with a date. This works for me because my sources don’t change, except to add data, which is usually stored in date directories anyway.

    You’re also wanting to archive the exported files, and sometimes those change? Surely, this is much less data? Of you’re like me, I’ll shoot 128xB and end up using a tiny fraction of the shots. I’m not sure what I’d do for that - probably BD-RW. The longevity isn’t great, but it’s by definition mutable data, and in any case the most recent version can be easily enough regenerated as long as I have the sidecar and source image secured.

    Burning the sidecar to disk is less about storage and more about backup, because that is mutable. I suppose an append backup snapshot to M-Disc periodically would be boots and suspenders, and frankly the sidecar data is so tiny I could probably append such snapshots to a single disc for years before it all gets used. Although… sidecar data would compress well. Probably simply tgz, then, since it’s always existed, and always will, even if gzip has been superseded by better algorithms.

    BTW, I just learned about the b3 hashing algorithm (about which I’m chagrined, because I thought I kept an eye out on the topic of compression and hashing). It’s astonishingly fast - for the verification part, is what I’m suggesting.