@mwlucas apologies for birdsite link, I know you wrote a book about tarsnap in the past. Did you investigate how this specific situation would count against quotas? I'm finding it hard to estimate what / if any cost will be generated by pruning old archives.
@mulander It's all accounting. Tarsnap will bill you for metadata back & forth. In this case, it will be "block 1 now only used in backups A, C, and E." Doesn't matter which order you delete in.
It won't re-download blocks you delete; it only updates the ledger.
IIRC --dry-run should give decent guesses on delete. It *should* 90% work from local tarsnap cache, unless you have corruption. (It'll use some bandwidth to verify local cache.)
Does that help?
@mwlucas yes it helps a lot. I wasn't sure if deletion won't result in re-packing existing archives. If I understand correctly it doesn't store on that level (archives+index) but on block level (+mapping). Makes complete sense now. Thank you!
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