On Mon, Jan 13, 2020 at 3:28 AM Gionatan Danti <g.danti@xxxxxxxxxx> wrote: > > Still, in at least one use case they are quite similar: single-volume > storage of virtual machine files, with vdisk-level snapshot. So lets say > I have a single big volume for storing virtual disk image file, and > using XFS reflink to take atomic, per file snapshot via a simple "cp > --reflink vdisk.img vdisk_snap.img". Is --reflink on XFS atomic? In particular for a VM file that's being used, that's possibly quite a lot of metadata on disk and in-flight in the host and in the guest. I ask because I'm not certain --reflink copies on Btrfs are atomic, I'll have to ask over there too. Whereas btrfs subvolume snapshots are considered atomic. -- Chris Murphy
