:: Re: [DNG] Long-term archiving versu…
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Author: Syeed Ali
To: dng
Subject: Re: [DNG] Long-term archiving versus medium fallibility
On Mon, 1 Nov 2021 08:11:54 -0400
Hendrik Boom <hendrik@???> wrote:

> Yet these files are also working files, are kept online, and
> legitinately need to be modified from time to time.

> My present method is to keep everything on my server, and make
> regular backups.

My first suggestion is to decide why you're keeping everything
together. Perhaps there needs to be a separation between

Convenience; everything in one place (and subject to the same
procedures, benefits and flaws)

Confidence; some things subject to enhanced archival techniques or
media, such as using M-DISC [1]

Perhaps there does not need to be a separation. Maybe the effort is
too high or the reward is not great enough. Make this decision.

Maybe unchanging media, such as your media archives (photographs,
video, poetry) can be on M-DISC locally, with a second copy offsite.

Thinking about M-DISC and changes, it makes me wonder if multi-track /
multi-session technology [2] is available to them. This would allow
the appending of data to either add more files, or "modify" existing
files (versioning in a sense).

> Currently I use rdiff-backup, which does have the ablity to keep
> older as well as newer versions of files on the same backup drive.

Does rdiff-backup have the ability to keep older versions on different
storage? If so, you could shunt those data to a more reliable medium.
It would also save you space for your "live" data, giving some
side-benefits like reduced cost.

> Now storage media deteriorate over time.
> It is necessary to read and transfer data from old media to new from
> time to time.

If these things can be solved or made less difficult, it would help
alleviate a lot of pressure on the rest of your backups. This is why I
suggested M-DISC [1]


As for your other thoughts, I have no experience. Regarding
filesystems, I think it was ZFS that you mean. [3]


1. https://en.wikipedia.org/wiki/M-DISC

2. Regarding multi-session, I'm unfamiliar with it but see:

"Red Book" (1980), regarding CD-ROMs in general

"Blue Book" (1995), regarding E-CD/CD+/CD Extra (Enhanced)

Is multi-session obscure knowledge? Maybe USB storage rose to
prominence at about the same time.

3. https://openzfs.github.io/openzfs-docs/Basic%20Concepts/Checksums.html