[Nottingham] Copy without copying?

[VM]

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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