> On Jun 26, 2017, at 22:45, Quincey Morris > <quinceymor...@rivergatesoftware.com> wrote: > >> On Jun 26, 2017, at 19:17 , Sandor Szatmari <admin.szatmari....@gmail.com> >> wrote: >> >> Are you talking about just a regular old copy or a copy in the sense of a >> time machine backup? Are these behaviors different on APFS? > > Yes and no. A regular old copy will create metadata for a new file, and point > back to the data blocks of the copied file. A time machine backup will create > a snapshot, which is effect a copy of all the metadata in the volume, with > the same shared pointers to the data blocks.
Yes, I felt the description of the copy on write behavior was intended to be universal to all copy operations not just a special operation reserved for time machine. But, my even more admittedly vague understanding did not allow me to confidently draw a distinction be tween the two. Thank you for tipping the scales. > > In both cases, the functionality relies on the copy-on-write behavior, which > works at the data block level, not the file level. Yes, this is very nice... > (The latter point is worth keeping in mind, because it means that deleting > files in APFS may not recover all of the file’s size into free space.) The ADC video stresses this point several times. > >> On Jun 26, 2017, at 19:38 , Rick Mann <rm...@latencyzero.com> wrote: >> >> But there's actually a POSIX "clone" API, and so I wonder if a copy is >> different from a clone. > > My (admittedly vague) understanding is that all file system copy operations > are expected to be clones. I would imagine the difference between the APIs to > be that a “copy" will do a traditional duplication if the source file is > uncloneable (e.g. on a non-APFS volume), but the “clone” would fail. > > But it would be a big hole if existing apps that copy items didn’t get the > cloning behavior by default. > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
