For LCOW currently we copy (or create) the scratch.vhdx for every single snapshot
so there ends up being a sandbox.vhdx in every directory seemingly unnecessarily. With the default scratch
size of 20GB the size on disk is about 17MB so there's a 17MB overhead per layer plus the time to copy the
file with every snapshot. Only the final sandbox.vhdx is actually used so this would be a nice little
optimization.
For WCOW we essentially do the exact same except copy the blank vhdx from the base layer.
Signed-off-by: Daniel Canter <dcanter@microsoft.com>
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