On Fri, 22 Nov 2013 01:47:43 -0800, Joshua Varghese wrote: > Hi, > > I'm trying to implement a mechanism for incremental backup using btrfs. > I have two hardisks and each has a btrfs partition on it. I am able to > take a snapshot of the source partition and send it to the backup disk > using the send-recieve mechanism. When I try to send an incremental > backup of a new snapshot with the previous snapshot as the parent btrfs > command complains (ERROR: could not find parent subvolume). The kernel > logs also record a error (kernel: could not find root 9). I've listed > the actual commands and their outputs below. Please let me know if you > need any more information. > > # btrfs sub create check_backup > /Create subvolume './check_backup/ > # touch check_backup/before_first_snap > # btrfs sub snapshot -r check_backup/ first_snap > /Create a readonly snapshot of 'check_backup/' in './first_snap'/ > # btrfs sub snapshot -r check_backup/ second_snap > /Create a readonly snapshot of 'check_backup/' in './second_snap'/ > > <second volume mounted at /mnt/gentoo/> > # btrfs send first_snap | btrfs receive /mnt/gentoo/backup/test/ > /At subvol first_snap// > //At subvol first_snap// > /# btrfs send -p first_snap second_snap/ | btrfs receive > /mnt/gentoo/backup/test/ > /At subvol second_snap/// > //At snapshot second_snap// > //ioctl(BTRFS_IOC_TREE_SEARCH, uuid, key 40e9283cdf98a796, UUID_KEY, > 0fc9a258f8cd8da7) ret=-1, //error: No such file or directory// > //ERROR: could not find parent subvolume// > / > /(kernel log): kernel: could not find root 9/ Works for me. How old is your kernel (which version)? You need 3.12 or better if you use the most recent btrfs-progs. New progs and old kernel doesn't work in this case, new kernel and old progs would work. > As I understand the send command would take a difference between the two > snapshots and the send it to the receive. I used the file mechanism > instead of the pipe and realized that the receive is the one that complains. > I'd also read in the documentation > (http://docs.oracle.com/cd/E37670_01/E37355/html/ol_sendrecv_btrfs.hml) > about clone source. I don't understand its implication in incremental > backup. > > Regards, > Josh -- 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
