> Care to share you rsync script?
Sure. It's a little raw, and makes some assumptions about my environment, but
it does the job other than the fact that it takes weeks to run. :)
In the below example, the "main" or source FS is mounted at "/mnt/btrfs", the
"backup" or target FS at "/mnt/btrfsbackup", and this script is located at
"/mnt/btrfs/backupscripts". I also run a slight variation of this script that
makes it only "catch up" on snapshots that don't already exist on the backup FS
simply by commenting out the rsync command directly above the echo that says
"Export resynced snapshot". If you don't comment that out, then the script
attempts to re-sync ALL snapshots, even ones that have already been copied over
in a previous run, effectively double checking that everything has already been
copied.
This script is as efficient as I know how to make it, as it uses the
--no-whole-file and --inplace rsync switches to prevent btrfs from thinking
lots of blocks have changed that haven't really changed and eating up lots of
space.
Also, an assumption is made that directly under /mnt/btrfs there are many
subvolumes, and that the snapshots for these subvolumes are stored under
/mnt/btrfs/snapshots/[subvol name]/[snap name].
Lastly, please note that I *DO* understand the purpose of the --bwlimit switch
for rsync. I've run it without that and it still takes weeks. It's only in
there now because it seemed to prevent issues I was having where the whole
system would lock up under heavy btrfs activity. I can't remember if that was
a problem I solved by switching out my SATA controller card or by upgrading my
kernel, but I don't believe I'm having that issue anymore.
FWIW.
#!/bin/bash
# The following script is for exporting snapshots from one drive to another.
# Putting the word "STOP" (all caps, without quotes) in stopexport.txt will
abort
# the process at the end of the current rsync job.
DATE=`date +%Y%m%d`
DATETIME=`date +%Y%m%d%H%M%S`
SCRIPTSFOLDER="/mnt/btrfs/backupscripts"
BACKUPFOLDER="/mnt/btrfs"
EXTERNALDRIVE="/mnt/btrfsbackup"
echo "Export Started `date`"
echo
# This will create all the snapshots in the original drive's snapshots folder
# on the export drive that don't exist on the export drive.
for PATHNAME in $BACKUPFOLDER/snapshots/*
do
if [ `cat $SCRIPTSFOLDER/stopexport.txt` = "STOP" ]; then
echo "STOP"
break
fi
SHARENAME=`basename $PATHNAME`
btrfs subvolume create $EXTERNALDRIVE/$SHARENAME
for SNAPPATH in $PATHNAME/*
do
echo $SNAPPATH
SNAPNAME=`basename $SNAPPATH`
if [ ! -d "$EXTERNALDRIVE/snapshots/$SHARENAME/$SNAPNAME" ]; then
rsync -avvP --delete --bwlimit=20000 --ignore-errors --no-whole-file
--inplace $SNAPPATH/ $EXTERNALDRIVE/$SHARENAME
mkdir -p $EXTERNALDRIVE/snapshots/$SHARENAME
btrfs subvolume snapshot $EXTERNALDRIVE/$SHARENAME
$EXTERNALDRIVE/snapshots/$SHARENAME/$SNAPNAME
echo "Export created snapshot
$EXTERNALDRIVE/snapshots/$SHARENAME/$SNAPNAME"
else
rsync -avvP --delete --bwlimit=20000 --ignore-errors --no-whole-file
--inplace $SNAPPATH/ $EXTERNALDRIVE/snapshots/$SHARENAME/$SNAPNAME
echo "Export resynced snapshot
$EXTERNALDRIVE/snapshots/$SHARENAME/$SNAPNAME"
fi
if [ `cat $SCRIPTSFOLDER/stopexport.txt` = "STOP" ]; then
echo "STOP"
break
fi
done;
done;
echo "Export Completed `date`"
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