backup

#!/bin/bash
# Note that when you make a new disk, you need to run fdisk and create a
# single partition of type 83 (Linux).  Then do the following:
# mkfs.ext4 -i 65536 -m 0 -L AML_BACKUP /dev/sdX1
# tune2fs -c 0 /dev/sdX1
#
# For btrfs, do:
#   parted /dev/sdX:
#     mklabel gpt
#     mkpart btrfs 0% 100%
#     name 1 AML_BACKUP
#   mkfs.btrfs -L AML_BACKUP /dev/sdX1
#
# Note that to copy from an old backup disk to a new one, you must do the
# following to preserve hard links (which is very important):
# rsync -aH /mnt/backup/ /mnt/backup2


# Fail on undefined variables.
set -u

# Fail on failure
set -e

mountpoint="/mnt/backup"
device="LABEL=AML_BACKUP"
curdate=`date +%Y-%m-%d`
backupdest="$mountpoint/$curdate"
email="aml-root@cs.byu.edu"
logfile="/var/log/backups/$curdate"
home="/users/home"

mkdir -p $(dirname $logfile)

# exclusion:
# DON'T PUT SPACES ANYWHERE HERE!  Also, make sure that paths start with a
# slash (/), especially if they're short names--otherwise it will exclude that
# name _anywhere_ in the tree.
exclude=(--exclude="**/home/kseppi/ipf/code" \
         --exclude="**/home/jlc/Windows?Documents" \
         --exclude="**/home/*/.config/google-chrome/**" \
        )

# Renice myself and all future children
renice +19 $$ 2>&1 | tee -a $logfile

# have echo write to the logfile as well as output to screen
function echo(){ builtin echo $@ 2>&1 | tee -a $logfile; }

# Mount the backup drive
echo
echo
echo "Beginning backup process at $(date)"
echo "Mounting"
# (what about failure):
#mount $device $mountpoint || echo "Already mounted."
if ! mount $device $mountpoint ; then
    if ! mount -t btrfs $device $mountpoint; then
        echo "Mount failed"
        exit 1
    fi
fi

# Find the previous backup.
lastdest=`ls -d $mountpoint/????-??-?? |grep -v '\.' |grep -v $curdate |tail -n 1`
echo "Backing up to $mountpoint with date $curdate"
echo "Previous backup: $lastdest"
# Only link to previous backup if a previous backup exists
rsync_link_options=""
if [ -d "$lastdest" ]; then
    rsync_link_options="--delete --link-dest=$lastdest --ignore-existing"
else
    echo "*No previous directory found. Backing up from scratch. If this is not a new backup disk, this indicates an error.*"
fi

# Create location
mkdir -p $backupdest 2>&1 | tee -a $logfile

# check disk status before backup
dfbefore="$(df -h)"

# Backup AML Stuff (git repositories, live backup, web pages, etc.)
echo "Rsyncing."

# Note that we do --delete for when a backup is redone on the same day.
if rsync -av --bwlimit=300m $rsync_link_options \
    ${exclude[@]} $home $backupdest 2>&1 | tee -a $logfile
then
    echo
    echo "Rsync succeeded."
else
    echo "Rsync failed.  This could be because of the common error:"
    echo '"some files vanished before they could be transferred"'
fi

# Note: the above rsync will probably put an error into $? (and thus
# killing the script) because the following is common:
#
# rsync warning: some files vanished before they could be transferred (code
# 24) at main.c(892)

# state of disks after backup
dfafter=$(df -h)

# Unmount the backup drive
echo "Umounting"
umount $mountpoint || echo "Couldn't unmount."

# Create a short version of the log (the full log is too big ~1G)
head -n30 $logfile > $logfile-short
echo ". . ." >> $logfile-short
echo "omitted many lines" >> $logfile-short
echo ". . ." >> $logfile-short
tail -n30 $logfile >> $logfile-short

# Email notification
echo "Sending email notification"
mail -s "AML Backup Finished: $(date)" $email << END
The backup process for AML is now complete.

Here's the state of the file server drives (df -h):
===========================================
Before the latest backup
$dfbefore

After the latest backup:
$dfafter

Here is what was written to the backup log.
(Note: ignore the message warning that some files
vanished before they could be transferred.)
===========================================
$(cat $logfile-short)
END

# get rid of the huge log file
rm $logfile