On Wed, Jan 08, 2014 at 12:02:06AM -0800, Marc MERLIN wrote: > On Tue, Jan 07, 2014 at 10:53:29AM +0000, Hugo Mills wrote: > > You need to move /mnt/btrfs_pool2/tmp_read_only_new to a different > > name as well. The send stream contains the name of the subvolume it > > wants to create, so it's trying to create a subvolume called > > "tmp_read_only_new" in /mnt/btrfs_pool2, and there's one there already. > > Aaah, got it, thanks. > > I'll contribute back a shell script that makes this much easier when I'm > done with it.
I've now spent enough time on this and have enough testing to release it. http://marc.merlins.org/perso/btrfs/post_2014-03-22_Btrfs-Tips_-Doing-Fast-Incremental-Backups-With-Btrfs-Send-and-Receive.html which points to http://marc.merlins.org/linux/scripts/btrfs-subvolume-backup Just for the archives, here is a working copy (the blog post above explains why it keeps multiple snapshots after the fact, and creates writeable ones on the destination, but basically this allows you to automatically boot from the latest snapshot (a writeable snapshot copy pointed to by a symlink tha tis kept up to date)): ---------------------------------------------------------------------------- #!/bin/bash # By Marc MERLIN <marc_s...@merlins.org> # License: GPL-2 or BSD at your choice. # Source: http://marc.merlins.org/linux/scripts/ # $Id: btrfs-subvolume-backup 958 2014-03-16 00:23:28Z svnuser $ # cron jobs might not have /sbin in their path. export PATH="$PATH:/sbin" set -o nounset set -o errexit set -o pipefail # From https://btrfs.wiki.kernel.org/index.php/Incremental_Backup # bash shortcut for `basename $0` PROG=${0##*/} lock=/var/run/$PROG usage() { cat <<EOF Usage: cd /mnt/source_btrfs_pool $PROG [--init] [--keep|-k num] [--dest hostname] volume_name /mnt/backup_btrfs_pool Options: --init: Print this help message and exit. --keep num: Keep the last snapshots for local backups (5 by default) --dest hostname: If present, ssh to that machine to make the copy. This will snapshot volume_name in a btrfs pool, and send the diff between it and the previous snapshot (volume_name.last) to another btrfs pool (on other drives) If your backup destination is another machine, you'll need to add a few ssh commands this script The num sanpshots to keep is to give snapshots you can recover data from and they get deleted after num runs. Set to 0 to disable (one snapshot will be kept since it's required for the next diff to be computed). EOF exit 0 } die () { msg=${1:-} # don't loop on ERR trap '' ERR rm $lock echo "$msg" >&2 echo >&2 # This is a fancy shell core dumper if echo $msg | grep -q 'Error line .* with status'; then line=`echo $msg | sed 's/.*Error line \(.*\) with status.*/\1/'` echo " DIE: Code dump:" >&2 nl -ba $0 | grep -3 "\b$line\b" >&2 fi exit 1 } # Trap errors for logging before we die (so that they can be picked up # by the log checker) trap 'die "Error line $LINENO with status $?"' ERR init="" # Keep the last 5 snapshots by default keep=5 TEMP=$(getopt --longoptions help,usage,init,keep:,dest: -o h,k:,d: -- "$@") || usage dest=localhost ssh="" # getopt quotes arguments with ' We use eval to get rid of that eval set -- $TEMP while : do case "$1" in -h|--help|--usage) usage shift ;; --keep|-k) shift keep=$1 shift ;; --dest|-d) shift dest=$1 ssh="ssh $dest" shift ;; --init) init=1 shift ;; --) shift break ;; *) echo "Internal error!" exit 1 ;; esac done [[ $keep < 1 ]] && die "Must keep at least one snapshot for things to work ($keep given)" DATE="$(date '+%Y%m%d_%H:%M:%S')" [[ $# != 2 ]] && usage vol="$1" dest_pool="$2" # shlock (from inn) does the right thing and grabs a lock for a dead process # (it checks the PID in the lock file and if it's not there, it # updates the PID with the value given to -p) if ! shlock -p $$ -f $lock; then echo "$lock held for $PROG, quitting" >&2 exit fi if [[ -z "$init" ]]; then test -e "${vol}_last" \ || die "Cannot sync $vol, ${vol}_last missing. Try --init?" src_snap="$(readlink -e ${vol}_last)" fi src_newsnap="${vol}_ro.$DATE" src_newsnaprw="${vol}_rw.$DATE" $ssh test -d "$dest_pool/" || die "ABORT: $dest_pool not a directory (on $dest)" btrfs subvolume snapshot -r "$vol" "$src_newsnap" # There is currently an issue that the snapshots to be used with "btrfs send" # must be physically on the disk, or you may receive a "stale NFS file handle" # error. This is accomplished by "sync" after the snapshot sync if [[ -n "$init" ]]; then btrfs send "$src_newsnap" | $ssh btrfs receive "$dest_pool/" else btrfs send -p "$src_snap" "$src_newsnap" | $ssh btrfs receive "$dest_pool/" fi # We make a read-write snapshot in case you want to use it for a chroot # and some testing with a writeable filesystem or want to boot from a # last good known snapshot. btrfs subvolume snapshot "$src_newsnap" "$src_newsnaprw" $ssh btrfs subvolume snapshot "$dest_pool/$src_newsnap" "$dest_pool/$src_newsnaprw" # Keep track of the last snapshot to send a diff against. ln -snf $src_newsnap ${vol}_last # The rw version can be used for mounting with subvol=vol_last_rw ln -snf $src_newsnaprw ${vol}_last_rw $ssh ln -snf $src_newsnaprw $dest_pool/${vol}_last_rw # How many snapshots to keep on the source btrfs pool (both read # only and read-write). ls -rd ${vol}_ro* | tail -n +$(( $keep + 1 ))| while read snap do btrfs subvolume delete "$snap" done ls -rd ${vol}_rw* | tail -n +$(( $keep + 1 ))| while read snap do btrfs subvolume delete "$snap" done # Same thing for destination (assume the same number of snapshots to keep, # you can change this if you really want). $ssh ls -rd $dest_pool/${vol}_ro* | tail -n +$(( $keep + 1 ))| while read snap do $ssh btrfs subvolume delete "$snap" done $ssh ls -rd $dest_pool/${vol}_rw* | tail -n +$(( $keep + 1 ))| while read snap do $ssh btrfs subvolume delete "$snap" done rm $lock ---------------------------------------------------------------------------- -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
