On Jan 27, 2014, at 7:03 AM, Hugo Mills <hugo@xxxxxxxxxxxxx> wrote: > On Mon, Jan 27, 2014 at 02:53:36PM +0100, KC wrote: >> I have been trying to understand how snapshots work (in BRTFS and in >> general), but I still have some questions, and would appreciate if >> someone could clear them for me. >> To make things easier, I tried to make most of them Yes/No questions: >> >> 1. When creating the filesystem, I only made btrfs partition with no >> subvolumes. Do I have to use subvolumes, or can I snapshot entire >> “/“? > > / (the top level of the FS) is a subvolume as well -- it's the only > one that can't be renamed or deleted, though. I'll point out a source of confusion I've had, and see new users have the same confusion quite often also. Within the file system hierarchy, / is a mount point. It could be that subvolume ID 5 is mounted there, which is how opensuse's default rootfs on Btrfs works. However, Fedora's / is a subvolume named root, the top level ID 5 subvolume isn't mounted by default. So / is not necessarily the top level of the file system. I'm not sure what to call the undeleteable ID 5 subvolume. It's the default subvolume, but if the user changes the default subvolume then it isn't. Calling it the default default is maybe more confusing. And calling it subvolume ID 5 is a bit confusing because subvolume ID 0 maps to 5, and many users are more familiar with subvol ID 0 than ID 5. And then if I have a subvolume within a subvolume mounted and do a btrfs list, it shows top level ID with a value other than 5. Anyway I really don't know what else to call the undeletable first subvolume. Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
