57 lines
3 KiB
Text
57 lines
3 KiB
Text
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[[!comment format=mdwn
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username="tapesafer"
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avatar="http://cdn.libravatar.org/avatar/8a62b25ea58309a6e15cac10a5c33f1d"
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subject="numcopies & force-trusting is ignored by fsck on readonly directory remotes?"
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date="2024-09-04T14:50:16Z"
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content="""
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I have old readonly backup media, say something like
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- `tapeA1/apples.txt`
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- `tapeA2/apples.txt`
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- `tapeB1/earth.svg`
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- `tapeB2/earth.svg`
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I use git-annex special directory remotes to be able to navigate the directory tree that lives on those media (e.g. to decide if and which media I need to find to copy a file from that I need).
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I added the remotes like so (they are too big to import with content):
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```
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git annex initremote tapeA1 type=directory directory=/tapes/tapeA1 encryption=none importtree=yes
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git annex import master:tapeA1 --from tapeA1 --no-content
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git annex merge --allow-unrelated-histories tapeA1/main
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```
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At some point I may buy new hardware and recreate those backup media as proper git-annex remotes, but wouldn't it be great to keep the existing backups as long as they show no sign of bitrot and together hold enough copies?
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Though, git-annex fsck behaves unexpected: It seems I cannot force trust these remotes nor does `--numcopies=0 --mincopies=0` have the desired effect.
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Concretely, when calling `git annex fsck --from=tapeA1 --numcopies=0 --mincopies=0 --trust=tapeA1 --force`,
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for every file that is still intact on tapeA1, git-annex fsck reports a failure as follows
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```
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fsck tapeA1/apples.txt
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Only these untrusted locations may have copies of tapeA1/apples.txt
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abc-def-ghi -- [tapeA1]
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Back it up to trusted locations with git-annex copy.
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failed
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```
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while I'd be happy to (semi)trust tapeA1 or to accept no copies whatsoever. So fsck ignores `--trust=tapeA1 --force` and/or `--numcopies=0 --mincopies=0` which are common git-annex options that should work for fsck?
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Ideally, I would be able to (semi)trust my readonly tape remotes (which likely should be behind a `--force` as it may lead to data loss in classical directory remote settings). Then I can use git-annex to index those tapes, but also to monitor their health via fsck (so I can over the years replace the tapes that are showing signs of corruption).
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As for the corruption, I emulated bitrot on a test directory remote, which then leads to a fsck failure as follows:
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```
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fsck tapeB2/earth.svg
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verification of content failed
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(checksum...)
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tapeB2/earth.svg: Bad file content; failed to drop fromtapeB2: dropping content from this remote is not supported because it is configured with importtree=yes
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```
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This suffices to detect tapes that should be replaced, and it's kinda expected that files cannot be dropped.
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Somehow fsck does not work as I would expect -- am I misunderstanding the numcopies/mincopies arguments here? Is there really no way to force-trust a directory remote, which to me seems appropriate in this case? Is there another way to achieve what I have in mind with git-annex?
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Thanks for this great piece of software – also use the assistant in another day-to-day usecase and it's simply great!
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"""]]
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