Re: subvols and parents - how?

[Christoph Anton Mitterer <calestyo@scientia.net>]

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On Tue, 2015-11-24 at 21:55 +0000, Hugo Mills wrote:
>    In practice, new content is checked by a number of people when
> it's
> put in, so the case of someone putting random poorly-thought-out crap
> in the wiki isn't particularly likely to happen.
Well... it may work in 99% cases... but there could something slip
through, which isn't as easy the case in manpages, which also tend to
be less messy than the huge pile of wiki pages where similar/related
things are described on different pages.

Imagine a case, a non-experienced user update the wiki saying that --
repair should be used, he may not even doing it in bad faith, perhaps
he had success with it and now writes a recipe.
It may take a while until someone of the more experienced guys notices
that and corrects it.
But if ", in the meantime had some fs corruptions,... I may experience
already severe problems by following that suggestion... (and while I do
have many backups of all my data, others may not, and if their life's
data is concerned, they'd be screwed).

So even if it takes you just a few hours to correct such rubbish, you
know that Murphy's law may still hit n people during that time ;-)


> Please feel free to add the things you'd like to see. As I said
> above, we do check the docs on the wiki as they're changed, so if
> you're wrong on some details, it won't be a major issue for very
> long. If you want to discuss details before you write something,
> start
> a conversation -- either on here, or on IRC (or even on the Talk
> pages
> of the wiki).
Well I can write a list together of things which I think should be part
of some more general documentation (i.e. less documentation about
options of the tools)... questions a complete newcomer to btrfs may
have who needs however more than "just a filesystem".


>    Note that the "parent" of send -p and of snapshots is not the same
> relationship as the "parent" (containing subvol) of the tree
> structure. This is an awkward nomenclature problem, and I'm not sure
> how to fix it.
Yeah, that was clear... :-)
Maybe call the "parent" from send -p "base" or something like that...
IMHO that would fit more as the parent there is more like a
"fundament".

Anyway, it's still not as bad as the usage of "RAID1" ;-)


> because
> you can't rename a subvol across another subvol boundary.
That's not quite clear to me... I had subvols like that:
/top/root/below-root
/top/below-top
and was able to move that to:
/top/root/below-top
/top/below-root

i.e. not just changing names but swapping as in:
mv /top/root/below-top /top/tmp
mv /top/below-root /top/root/below-root
mv /top/tmp /top/below-top

with top, root, below-top and below-root all being the same subvols


Thanks a lot for your explanations :)

Chris.

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