From 7ac1988d750e35281ace033e58aaf0d21872d8b5 Mon Sep 17 00:00:00 2001
From: Jochen Welzel <jochen.welzel@de.clara.net>
Date: Thu, 7 Jan 2021 12:10:48 +0100
Subject: [PATCH] add some improvements

---
 libvirt-zsh-backup.sh | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/libvirt-zsh-backup.sh b/libvirt-zsh-backup.sh
index 799e822..88f9650 100644
--- a/libvirt-zsh-backup.sh
+++ b/libvirt-zsh-backup.sh
@@ -35,6 +35,8 @@ DATE=$(date "+%Y%m%d%H%M")
 DATE30=$(date -d "-30day" "+%Y%m%d")
 SNAPNAME="backup_$DATE"
 
+echo "$(date +%Y-%m-%d_%H:%M): Starting Backup of $VM"
+
 abortFunction()
 {
     zfs set backup:success="false" $SRCZFS
@@ -93,21 +95,32 @@ done
 virsh snapshot-delete $VM $SNAPNAME --metadata
 
 SUCCESS=$(zfs get backup:success -H -o value $SRCZFS)
+LASTBACKUP=$(zfs get backup:date -H -o value $SRCZFS)
 if [[ $SUCCESS == "true" ]]
 then
-    LASTBACKUP=$(zfs get backup:date -H -o value $SRCZFS)
     LASTSNAP="backup_$LASTBACKUP"
     echo "Sending incremental snapshot from $LASTSNAP"
     zfs send -R -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
 else
-    echo "Sending full snapshot"
-    zfs send -R "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
+    if [[ $LASTBACKUP != "-" ]]
+    then
+        LASTSNAP="backup_$LASTBACKUP"
+	echo "Trying to send incremental snapshot from $LASTSNAP"
+	zfs send -R -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
+    else 
+        echo "Sending full snapshot"
+        zfs send -R "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
+    fi
 fi
 if [ $? -eq 0 ]
 then
     zfs set backup:success="true" $SRCZFS
     zfs set backup:date="$DATE" $SRCZFS
-    zfs destroy "$SRCZFS"@"$LASTSNAP"
+    if [ -n $LASTSNAP ]
+    then
+	echo "Deleting old ZFS snapshot $LASTSNAP"
+        zfs destroy "$SRCZFS"@"$LASTSNAP"
+    fi
 else
     abortFunction
 fi