That makes sense to me. Thank you for taking the time to explain. Thomas
On Tue, May 7, 2019 at 4:33 PM Dominic Giampaolo <dgiampa...@apple.com> wrote: > > > I accept that it's currently not possible - but just to help me > understand this, could you please elaborate: > > > > In theory, would it be possible to share a cloned file between two > volumes? Since they're in the same container, and the space management is > container-wide, could this be made possible? Or are there technical reason > why this couldn't work at all (such as that IDs needed to manage this are > not sharable between volumes)? > > > Space management (i.e. is this block allocated or not) is shared. But > cloning introduces another layer which is a reference count the blocks and > that is not shared between volumes within a container. Further it's > complicated by snapshots and the management of the reference counts across > snapshots and the live view of the file system. > > Consider what would happen if you cloned a file between two volumes, took > a snapshot on both volumes, modified part of the file on one of the volumes > then deleted it on the other. Managing the reference counting would be a > nightmare, especially since you'd have to manage locking some new shared > data structure between two different volumes. > > We'll definitely think about it but as always, a compelling use case is > needed to justify the work. In other words, we can't just do something > because it would be kinda cool - there has to be a good reason to expend > the effort required to do it. > > > --dominic > >
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