[Nottingham] Copy without copying?

[J J]

Ta - just got a demo working and now have a very happy colleague.

On Fri, 7 Jun 2019 at 15:38, VM via Nottingham <
nottingham at mailman.lug.org.uk> wrote:

> overlayfs is your friend :)
>
> On June 7, 2019 2:12:21 PM UTC, J J via Nottingham <
> nottingham at mailman.lug.org.uk> wrote:
> >I have some tests I'd like to run and in order to get them going the
> >first
> >thing I can to do is copy a large(ish) folder structure that can be
> >read/written by the tests. This copy is then discarded.
> >The copying is wasteful in terms of time and disc space, so I'd like to
> >avoid having to do that.
> >Clearly any changes could be record as a difference, so my question is:
> >
> >With Ext4, is there some magic way I can create and ad hoc
> >"differencing
> >volume" that appear to be like a copy but isn't. The tests can do what
> >they
> >like and that the whole thing gets chucked.
> >i.e. avoiding the copy operation
> >
> >I'm pretty sure if we had ZFS or something this would be possible, but
> >that's not the case here. Wondering if FUSE or something can be used to
> >fake it.
> >
> >My current reading suggests the answer is "No", but I thought I'd ask
> >some
> >experts.
> >
> >J.
>
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