I'm not sure I could fully understand the desired achievement but it sounds like (or this would be an example of selective perception) it's somehow related with "creating reproducible snapshots" (https://unix.stackexchange.com/q/462451/65781), no? Chris Murphy <lists@xxxxxxxxxxxxxxxxx>, 14 Eki 2018 Paz, 02:05 tarihinde şunu yazdı: > > On Sat, Oct 13, 2018 at 4:28 PM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > > Is it practical and desirable to make Btrfs based OS installation > > images reproducible? Or is Btrfs simply too complex and > > non-deterministic? [1] > > > > The main three problems with Btrfs right now for reproducibility are: > > a. many objects have uuids other than the volume uuid; and mkfs only > > lets us set the volume uuid > > b. atime, ctime, mtime, otime; and no way to make them all the same > > c. non-deterministic allocation of file extents, compression, inode > > assignment, logical and physical address allocation > > d. generation, just pick a consistent default because the entire image > is made with mkfs and then never rw mounted so it's not a problem > > > - Possibly disallow subvolumes and snapshots > > There's no actual mechanism to do either of these with mkfs, so it's > not a problem. And if a sprout is created, it's fine for newly created > subvolumes to follow the usual behavior of having unique UUID and > incrementing generation. Thing is, the sprout will inherit the seeds > preset chunk uuid, which while it shouldn't cause a problem is a kind > of violation of uuid uniqueness; but ultimately I'm not sure how big > of a problem it is for such uuids to spread. > > > > -- > Chris Murphy
