bookmark support messy: not all options are supported by zfs, determining changed datasets also not possible. on hold for now

Revert "Feature/ssh mux"

README.md

@@ -6,8 +6,8 @@ Introduction
 ZFS autobackup is used to periodicly backup ZFS filesystems to other locations. This is done using the very effcient zfs send and receive commands.
 
 It has the following features:
-* Automaticly selects filesystems to backup by looking at a simple ZFS property.
-* Creates consistent snapshots.
+* Automaticly selects filesystems to backup by looking at a simple ZFS property. (recursive)
+* Creates consistent snapshots. (takes all snapshots at once, atomic.)
 * Multiple backups modes:
   * "push" local data to a backup-server via SSH.
   * "pull" remote data from a server via SSH and backup it locally.
@@ -23,19 +23,21 @@ It has the following features:
 * Easy installation:
   * Only one host needs the zfs_autobackup script. The other host just needs ssh and the zfs command.
   * Written in python and uses zfs-commands, no 3rd party dependencys or libraries.
+  * No seperate config files or properties. Just one command you can copy/paste in your backup script.
 
 Usage
 ====
 ```
 usage: zfs_autobackup [-h] [--ssh-source SSH_SOURCE] [--ssh-target SSH_TARGET]
-                      [--ssh-cipher SSH_CIPHER] [--keep-source KEEP_SOURCE]
-                      [--keep-target KEEP_TARGET] [--no-snapshot] [--no-send]
-                      [--resume] [--strip-path STRIP_PATH] [--destroy-stale]
+                      [--keep-source KEEP_SOURCE] [--keep-target KEEP_TARGET]
+                      [--no-snapshot] [--no-send] [--resume]
+                      [--strip-path STRIP_PATH] [--destroy-stale]
                       [--clear-refreservation] [--clear-mountpoint]
-                      [--rollback] [--compress] [--test] [--verbose] [--debug]
+                      [--filter-properties FILTER_PROPERTIES] [--rollback]
+                      [--test] [--verbose] [--debug]
                       backup_name target_fs
 
-ZFS autobackup v2.1
+ZFS autobackup v2.2
 
 positional arguments:
   backup_name           Name of the backup (you should set the zfs property
@@ -51,8 +53,6 @@ optional arguments:
   --ssh-target SSH_TARGET
                         Target host to push backup to. (user@hostname) Default
                         local.
-  --ssh-cipher SSH_CIPHER
-                        SSH cipher to use (default None)
   --keep-source KEEP_SOURCE
                         Number of days to keep old snapshots on source.
                         Default 30.
@@ -64,7 +64,10 @@ optional arguments:
   --no-send             dont send snapshots (usefull to only do a cleanup)
   --resume              support resuming of interrupted transfers by using the
                         zfs extensible_dataset feature (both zpools should
-                        have it enabled)
+                        have it enabled) Disadvantage is that you need to use
+                        zfs recv -A if another snapshot is created on the
+                        target during a receive. Otherwise it will keep
+                        failing.
   --strip-path STRIP_PATH
                         number of directory to strip from path (use 1 when
                         cloning zones between 2 SmartOS machines)
@@ -77,10 +80,13 @@ optional arguments:
   --clear-mountpoint    Sets canmount=noauto property, to prevent the received
                         filesystem from mounting over existing filesystems.
                         (recommended)
+  --filter-properties FILTER_PROPERTIES
+                        Filter properties when receiving filesystems. Can be
+                        specified multiple times. (Example: If you send data
+                        from Linux to FreeNAS, you should filter xattr)
   --rollback            Rollback changes on the target before starting a
                         backup. (normally you can prevent changes by setting
                         the readonly property on the target_fs to on)
-  --compress            use compression during zfs send/recv
   --test                dont change anything, just show what would be done
                         (still does all read-only operations)
   --verbose             verbose output
@@ -131,7 +137,7 @@ First install the ssh-key on the server that you specify with --ssh-source or --
 
 Method 1: Run the script on the backup server and pull the data from the server specfied by --ssh-source. This is usually the preferred way and prevents a hacked server from accesing the backup-data:
 ```
-root@fs1:/home/psy# ./zfs_autobackup --ssh-source root@1.2.3.4 smartos01_fs1 fs1/zones/backup/zfsbackups/smartos01.server.com --verbose --compress
+root@fs1:/home/psy# ./zfs_autobackup --ssh-source root@1.2.3.4 smartos01_fs1 fs1/zones/backup/zfsbackups/smartos01.server.com --verbose
 Getting selected source filesystems for backup smartos01_fs1 on root@1.2.3.4
 Selected: zones (direct selection)
 Selected: zones/1eb33958-72c1-11e4-af42-ff0790f603dd (inherited selection)
@@ -160,12 +166,63 @@ All done
 ```
 
 Tips
-----
+====
 
  * Set the ```readonly``` property of the target filesystem to ```on```. This prevents changes on the target side. If there are changes the next backup will fail and will require a zfs rollback. (by using the --rollback option for example)
  * Use ```--clear-refreservation``` to save space on your backup server.
  * Use ```--clear-mountpoint``` to prevent the target server from mounting the backupped filesystem in the wrong place during a reboot. If this happens on systems like SmartOS or Openindia, svc://filesystem/local wont be able to mount some stuff and you need to resolve these issues on the console.
 
+Speeding up SSH and prevent connection flooding
+-----------------------------------------------
+
+Add this to your ~/.ssh/config:
+```
+Host *
+    ControlPath ~/.ssh/control-master-%r@%h:%p
+    ControlMaster auto
+    ControlPersist 3600
+```
+
+This will make all your ssh connections persistent and greatly speed up zfs_autobackup for jobs with short intervals.
+
+Thanks @mariusvw :)
+
+
+Specifying ssh port or options
+------------------------------
+
+The correct way to do this is by creating ~/.ssh/config:
+```
+Host smartos04
+    Hostname 1.2.3.4
+    Port 1234
+    user root
+    Compression yes
+```
+
+This way you can just specify smartos04
+
+Also uses compression on slow links.
+
+Look in man ssh_config for many more options.
+
+Troubleshooting
+===============
+
+`cannot receive incremental stream: invalid backup stream`
+
+This usually means you've created a new snapshot on the target side during a backup.
+ * Solution 1: Restart zfs_autobackup and make sure you dont use --resume. If you did use --resume, be sure to "abort" the recveive on the target side with zfs recv -A.
+ * Solution 2: Destroy the newly created snapshot and restart zfs_autobackup.
+
+
+`internal error: Invalid argument`
+
+In some cases (Linux -> FreeBSD) this means certain properties are not fully supported on the target system.
+
+Try using something like: --filter-properties xattr
+
+
 Restore example
 ===============
 
@@ -178,17 +235,6 @@ root@fs1:/home/psy#  zfs send fs1/zones/backup/zfsbackups/smartos01.server.com/z
 
 After that you can rename the disk image from the temporary location to the location of a new SmartOS machine you've created.
 
-Snapshotting example
-====================
-
-Sending huge snapshots cant be resumed when a connection is interrupted: Next time zfs_autobackup is started, the whole snapshot will be transferred again. For this reason you might want to have multiple small snapshots.
-
-The --no-send option can be usefull for this. This way you can already create small snapshots every few hours:
-````
-[root@smartos2 ~]# zfs_autobackup --ssh-source root@smartos1 smartos1_freenas1 zones --verbose --ssh-cipher chacha20-poly1305@openssh.com --no-send
-````
-
-Later when our freenas1 server is ready we can use the same command without the --no-send at freenas1. At that point the server will receive all the small snapshots up to that point.
 
 
 

zfs_autobackup

@@ -1,9 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # -*- coding: utf8 -*-
-
-
-
-
 from __future__ import print_function
 import os
 import sys
@@ -11,9 +7,8 @@ import re
 import traceback
 import subprocess
 import pprint
-import cStringIO
 import time
-
+import shlex
 
 def error(txt):
     print(txt, file=sys.stderr)
@@ -40,10 +35,6 @@ def run(cmd, input=None, ssh_to="local", tab_split=False, valid_exitcodes=[ 0 ],
     #use ssh?
     if ssh_to != "local":
         encoded_cmd.extend(["ssh", ssh_to])
-        if args.ssh_cipher:
-            encoded_cmd.extend(["-c", args.ssh_cipher])
-        if args.compress:
-            encoded_cmd.append("-C")
 
 
         #make sure the command gets all the data in utf8 format:
@@ -104,22 +95,24 @@ def zfs_get_selected_filesystems(ssh_to, backup_name):
     for source_filesystem in source_filesystems:
         (name,value,source)=source_filesystem
         if value=="false":
-            verbose("Ignoring: {0} (disabled)".format(name))
+            verbose("Ignored : {0} (disabled)".format(name))
 
         else:
-            if source=="local":
-                selected_filesystems.append(name)
+            if source=="local" and ( value=="true" or value=="child"):
                 direct_filesystems.append(name)
+
+            if source=="local" and value=="true":
+                selected_filesystems.append(name)
                 verbose("Selected: {0} (direct selection)".format(name))
-            elif source.find("inherited from ")==0:
+            elif source.find("inherited from ")==0 and (value=="true" or value=="child"):
                 inherited_from=re.sub("^inherited from ", "", source)
                 if inherited_from in direct_filesystems:
                     selected_filesystems.append(name)
                     verbose("Selected: {0} (inherited selection)".format(name))
                 else:
-                    verbose("Ignored: {0} (already a backup)".format(name))
+                    verbose("Ignored : {0} (already a backup)".format(name))
             else:
-                vebose("Ignored: {0} ({0})".format(source))
+                verbose("Ignored : {0} (only childs)".format(name))
 
     return(selected_filesystems)
 
@@ -150,6 +143,10 @@ def zfs_destroy_snapshots(ssh_to, snapshots):
         [ "xargs", "-0", "-n", "1", "zfs", "destroy", "-d" ]
     )
 
+def zfs_destroy_bookmark(ssh_to, bookmark):
+
+    run(ssh_to=ssh_to, test=args.test, valid_exitcodes=[ 0,1 ], cmd=[ "zfs", "destroy", bookmark ])
+
 """destroy list of filesystems """
 def zfs_destroy(ssh_to, filesystems, recursive=False):
 
@@ -166,37 +163,51 @@ test_snapshots={}
 
 
 
-"""create snapshot on multiple filesystems at once (atomicly)"""
+"""create snapshot on multiple filesystems at once (atomicly per pool)"""
 def zfs_create_snapshot(ssh_to, filesystems, snapshot):
 
-    cmd=[ "zfs", "snapshot" ]
 
+    #collect per pool, zfs can only take atomic snapshots per pool
+    pools={}
     for filesystem in filesystems:
-        cmd.append(filesystem+"@"+snapshot)
+        pool=filesystem.split('/')[0]
+        if pool not in pools:
+            pools[pool]=[]
+        pools[pool].append(filesystem)
 
-        #in testmode we dont actually make changes, so keep them in a list to simulate
-        if args.test:
-            if not ssh_to in test_snapshots:
-                test_snapshots[ssh_to]={}
-            if not filesystem in test_snapshots[ssh_to]:
-                test_snapshots[ssh_to][filesystem]=[]
-            test_snapshots[ssh_to][filesystem].append(snapshot)
+    for pool in pools:
+        cmd=[ "zfs", "snapshot" ]
+        for filesystem in pools[pool]:
+            cmd.append(filesystem+snapshot)
 
-    run(ssh_to=ssh_to, tab_split=False, cmd=cmd, test=args.test)
+            # #in testmode we dont actually make changes, so keep them in a list to simulate
+            # if args.test:
+            #     if not ssh_to in test_snapshots:
+            #         test_snapshots[ssh_to]={}
+            #     if not filesystem in test_snapshots[ssh_to]:
+            #         test_snapshots[ssh_to][filesystem]=[]
+            #     test_snapshots[ssh_to][filesystem].append(snapshot)
+
+        run(ssh_to=ssh_to, tab_split=False, cmd=cmd, test=args.test)
 
 
 """get names of all snapshots for specified filesystems belonging to backup_name
 
 return[filesystem_name]=[ "snashot1", "snapshot2", ... ]
 """
-def zfs_get_snapshots(ssh_to, filesystems, backup_name):
+def zfs_get_snapshots(ssh_to, filesystems, backup_name, also_bookmarks=False):
 
     ret={}
 
     if filesystems:
+        if also_bookmarks:
+            fstype="snapshot,bookmark"
+        else:
+            fstype="snapshot"
+
         #TODO: get rid of ugly errors for non-existing target filesystems
         cmd=[
-            "zfs", "list", "-d", "1", "-r", "-t" ,"snapshot", "-H", "-o", "name"
+            "zfs", "list", "-d", "1", "-r", "-t" ,fstype, "-H", "-o", "name", "-s", "createtxg"
         ]
         cmd.extend(filesystems)
 
@@ -204,30 +215,92 @@ def zfs_get_snapshots(ssh_to, filesystems, backup_name):
 
 
         for snapshot in snapshots:
-            (filesystem, snapshot_name)=snapshot.split("@")
-            if re.match("^"+backup_name+"-[0-9]*$", snapshot_name):
-                if not filesystem in ret:
-                    ret[filesystem]=[]
-                ret[filesystem].append(snapshot_name)
+            if "@" in snapshot:
+                (filesystem, snapshot_name)=snapshot.split("@")
+                snapshot_name="@"+snapshot_name
+            else:
+                (filesystem, snapshot_name)=snapshot.split("#")
+                snapshot_name="#"+snapshot_name
 
+            if re.match("^[@#]"+backup_name+"-[0-9]*$", snapshot_name):
+                ret.setdefault(filesystem,[]).append(snapshot_name)
+
+        #TODO: get rid of this or make a more generic caching/testing system. (is it still needed, since the allow_empty-function?)
         #also add any test-snapshots that where created with --test mode
-        if args.test:
-            if ssh_to in test_snapshots:
-                for filesystem in filesystems:
-                    if filesystem in test_snapshots[ssh_to]:
-                        if not filesystem in ret:
-                            ret[filesystem]=[]
-                        ret[filesystem].extend(test_snapshots[ssh_to][filesystem])
+        # if args.test:
+        #     if ssh_to in test_snapshots:
+        #         for filesystem in filesystems:
+        #             if filesystem in test_snapshots[ssh_to]:
+        #                 if not filesystem in ret:
+        #                     ret[filesystem]=[]
+        #                 ret[filesystem].extend(test_snapshots[ssh_to][filesystem])
 
     return(ret)
 
 
+# """get names of all bookmarks for specified filesystems belonging to backup_name
+#
+# return[filesystem_name]=[ "bookmark1", "bookmark2", ... ]
+# """
+# def zfs_get_bookmarks(ssh_to, filesystems, backup_name):
+#
+#     ret={}
+#
+#     if filesystems:
+#         #TODO: get rid of ugly errors for non-existing target filesystems
+#         cmd=[
+#             "zfs", "list", "-d", "1", "-r", "-t" ,"bookmark", "-H", "-o", "name", "-s", "createtxg"
+#         ]
+#         cmd.extend(filesystems)
+#
+#         bookmarks=run(ssh_to=ssh_to, tab_split=False, cmd=cmd, valid_exitcodes=[ 0 ])
+#
+#         for bookmark in bookmarks:
+#             (filesystem, bookmark_name)=bookmark.split("#")
+#             if re.match("^"+backup_name+"-[0-9]*$", bookmark_name):
+#                 ret.setdefault(filesystem,[]).append(bookmark_name)
+#
+#     return(ret)
+
+
+def default_tag():
+    return("zfs_autobackup:"+args.backup_name)
+
+"""hold a snapshot so it cant be destroyed accidently by admin or other processes"""
+def zfs_hold_snapshot(ssh_to, snapshot, tag=None):
+    cmd=[
+        "zfs", "hold", tag or default_tag(), snapshot
+    ]
+
+    run(ssh_to=ssh_to, test=args.test, tab_split=False, cmd=cmd, valid_exitcodes=[ 0, 1 ])
+
+
+"""release a snapshot"""
+def zfs_release_snapshot(ssh_to, snapshot, tag=None):
+    cmd=[
+        "zfs", "release", tag or default_tag(), snapshot
+    ]
+
+    run(ssh_to=ssh_to, test=args.test, tab_split=False, cmd=cmd, valid_exitcodes=[ 0, 1 ])
+
+
+"""bookmark a snapshot"""
+def zfs_bookmark_snapshot(ssh_to, snapshot):
+    (filesystem, snapshot_name)=snapshot.split("@")
+    cmd=[
+        "zfs", "bookmark", snapshot, '#'+snapshot_name
+    ]
+
+    run(ssh_to=ssh_to, test=args.test, tab_split=False, cmd=cmd, valid_exitcodes=[ 0 ])
+
 
 """transfer a zfs snapshot from source to target. both can be either local or via ssh.
 
 
 TODO:
 
+(parially implemented, local buffer is a bit more annoying to do)
+
 buffering: specify buffer_size to use mbuffer (or alike) to apply buffering where neccesary
 
 local to local:
@@ -240,7 +313,6 @@ remote send -> remote buffer -> ssh -> local buffer -> local receive
 remote to remote:
 remote send -> remote buffer -> ssh -> local buffer -> ssh -> remote buffer -> remote receive
 
-TODO: can we string together all the zfs sends and recvs, so that we only need to use 1 ssh connection? should be faster if there are many small snaphots
 
 
 
@@ -253,15 +325,20 @@ def zfs_transfer(ssh_source, source_filesystem, first_snapshot, second_snapshot,
 
     if ssh_source != "local":
         source_cmd.extend([ "ssh", ssh_source ])
-        if args.ssh_cipher:
-            source_cmd.extend(["-c", args.ssh_cipher])
-        if args.compress:
-            source_cmd.append("-C")
 
     source_cmd.extend(["zfs", "send",  ])
 
+    #all kind of performance options:
+    source_cmd.append("-L") # large block support
+    source_cmd.append("-e") # WRITE_EMBEDDED, more compact stream
+    source_cmd.append("-c") # use compressed WRITE records
+    if not args.resume:
+        source_cmd.append("-D") # dedupped stream, sends less duplicate data
+
+
+
     #only verbose in debug mode, lots of output
-    if args.debug:
+    if args.debug :
         source_cmd.append("-v")
 
 
@@ -275,31 +352,41 @@ def zfs_transfer(ssh_source, source_filesystem, first_snapshot, second_snapshot,
         verbose("RESUMING "+txt)
 
     else:
-        source_cmd.append("-p")
+        # source_cmd.append("-p")
 
         if first_snapshot:
-            source_cmd.extend([ "-i", first_snapshot ])
+            source_cmd.append( "-i")
+            #TODO: fix these horrible escaping hacks
+            if ssh_source != "local":
+                source_cmd.append( "'"+first_snapshot+"'" )
+            else:
+                source_cmd.append( first_snapshot )
 
         if ssh_source != "local":
-            source_cmd.append("'" + source_filesystem + "@" + second_snapshot + "'")
+            source_cmd.append("'" + source_filesystem + second_snapshot + "'")
         else:
-            source_cmd.append(source_filesystem + "@" + second_snapshot)
+            source_cmd.append(source_filesystem + second_snapshot)
 
         verbose(txt)
 
+    if args.buffer and args.ssh_source!="local":
+        source_cmd.append("|mbuffer -m {}".format(args.buffer))
+
+
     #### build target command
     target_cmd=[]
 
     if ssh_target != "local":
         target_cmd.extend([ "ssh", ssh_target ])
-        if args.ssh_cipher:
-            target_cmd.extend(["-c", args.ssh_cipher])
-        if args.compress:
-            target_cmd.append("-C")
 
     target_cmd.extend(["zfs", "recv", "-u" ])
 
-    #also verbose in --verbose mode so we can see the transfer speed when its completed
+    # filter certain properties on receive (usefull for linux->freebsd in some cases)
+    if args.filter_properties:
+        for filter_property in args.filter_properties:
+            target_cmd.extend([ "-x" , filter_property ])
+
+    #also verbose in --verbose moqde so we can see the transfer speed when its completed
     if args.verbose or args.debug:
         target_cmd.append("-v")
 
@@ -312,6 +399,8 @@ def zfs_transfer(ssh_source, source_filesystem, first_snapshot, second_snapshot,
     else:
         target_cmd.append(target_filesystem)
 
+    if args.buffer and  args.ssh_target!="local":
+        target_cmd.append("|mbuffer -m {}".format(args.buffer))
 
 
     #### make sure parent on target exists
@@ -332,15 +421,16 @@ def zfs_transfer(ssh_source, source_filesystem, first_snapshot, second_snapshot,
     source_proc.stdout.close() # Allow p1 to receive a SIGPIPE if p2 exits.
     target_proc.communicate()
 
-    if source_proc.returncode:
-        raise(subprocess.CalledProcessError(source_proc.returncode, source_cmd))
+    if not args.ignore_transfer_errors:
+        if source_proc.returncode:
+            raise(subprocess.CalledProcessError(source_proc.returncode, source_cmd))
 
-    #zfs recv sometimes gives an exitcode 1 while the transfer was succesfull, therefore we ignore exit 1's and do an extra check to see if the snapshot is there.
-    if target_proc.returncode and target_proc.returncode!=1:
-        raise(subprocess.CalledProcessError(target_proc.returncode, target_cmd))
+        #zfs recv sometimes gives an exitcode 1 while the transfer was succesfull, therefore we ignore exit 1's and do an extra check to see if the snapshot is there.
+        if target_proc.returncode and target_proc.returncode!=1:
+            raise(subprocess.CalledProcessError(target_proc.returncode, target_cmd))
 
     debug("Verifying if snapshot exists on target")
-    run(ssh_to=ssh_target, cmd=["zfs", "list", target_filesystem+"@"+second_snapshot ])
+    run(ssh_to=ssh_target, cmd=["zfs", "list", target_filesystem+second_snapshot ])
 
 
 
@@ -387,8 +477,8 @@ def determine_destroy_list(snapshots, days):
             else:
                 time_secs=int(time_str)
                 # verbose("time_secs"+time_str)
-            if (now-time_secs) > (24 * 3600 * days):
-                ret.append(filesystem+"@"+snapshot)
+            if (now-time_secs) >= (24 * 3600 * days):
+                ret.append(filesystem+snapshot)
 
     return(ret)
 
@@ -397,6 +487,28 @@ def lstrip_path(path, count):
     return("/".join(path.split("/")[count:]))
 
 
+"""get list of filesystems that are changed, compared to the latest snapshot"""
+def zfs_get_unchanged_filesystems(ssh_to, filesystems):
+
+    ret=[]
+    for ( filesystem, snapshot_list ) in filesystems.items():
+        latest_snapshot=snapshot_list[-1]
+
+        #make sure its a snapshot and not a bookmark
+        latest_snapshot="@"+latest_snapshot[:1]
+
+        cmd=[
+            "zfs", "get","-H" ,"-ovalue", "written"+latest_snapshot, filesystem
+        ]
+
+        output=run(ssh_to=ssh_to, tab_split=False, cmd=cmd, valid_exitcodes=[ 0 ])
+
+        if output[0]=="0B":
+            ret.append(filesystem)
+            verbose("No changes on {}".format(filesystem))
+
+    return(ret)
+
 
 def zfs_autobackup():
 
@@ -428,16 +540,6 @@ def zfs_autobackup():
         target_filesystems.append(args.target_fs + "/" + lstrip_path(source_filesystem, args.strip_path))
 
 
-    ### creating snapshots
-    # this is one of the first things we do, so that in case of failures we still have snapshots.
-
-    #create new snapshot?
-    if not args.no_snapshot:
-        new_snapshot_name=args.backup_name+"-"+time.strftime("%Y%m%d%H%M%S")
-        verbose("Creating source snapshot {0} on {1} ".format(new_snapshot_name, args.ssh_source))
-        zfs_create_snapshot(args.ssh_source, source_filesystems, new_snapshot_name)
-
-
     ### get resumable transfers
     resumable_target_filesystems={}
     if args.resume:
@@ -446,12 +548,44 @@ def zfs_autobackup():
         debug("Resumable filesystems: "+str(pprint.pformat(resumable_target_filesystems)))
 
 
-    ### get all snapshots of all selected filesystems on both source and target
-
+    ### get all snapshots of all selected filesystems
     verbose("Getting source snapshot-list from {0}".format(args.ssh_source))
-    source_snapshots=zfs_get_snapshots(args.ssh_source, source_filesystems, args.backup_name)
+    source_snapshots=zfs_get_snapshots(args.ssh_source, source_filesystems, args.backup_name, also_bookmarks=True)
     debug("Source snapshots: " + str(pprint.pformat(source_snapshots)))
+    # source_bookmarks=zfs_get_bookmarks(args.ssh_source, source_filesystems, args.backup_name)
+    # debug("Source bookmarks: " + str(pprint.pformat(source_bookmarks)))
 
+
+    #create new snapshot?
+    if not args.no_snapshot:
+        #determine which filesystems changed since last snapshot
+        if not args.allow_empty:
+            verbose("Determining unchanged filesystems")
+            unchanged_filesystems=zfs_get_unchanged_filesystems(args.ssh_source, source_snapshots)
+        else:
+            unchanged_filesystems=[]
+
+        snapshot_filesystems=[]
+        for source_filesystem in source_filesystems:
+            if source_filesystem not in unchanged_filesystems:
+                snapshot_filesystems.append(source_filesystem)
+
+
+        #create snapshot
+        if snapshot_filesystems:
+            new_snapshot_name="@"+args.backup_name+"-"+time.strftime("%Y%m%d%H%M%S")
+            verbose("Creating source snapshot {0} on {1} ".format(new_snapshot_name, args.ssh_source))
+            zfs_create_snapshot(args.ssh_source, snapshot_filesystems, new_snapshot_name)
+        else:
+            verbose("No changes at all, not creating snapshot.")
+
+
+        #add it to the list of source filesystems
+        for snapshot_filesystem in snapshot_filesystems:
+            source_snapshots.setdefault(snapshot_filesystem,[]).append(new_snapshot_name)
+
+
+    #### get target snapshots
     target_snapshots={}
     try:
         verbose("Getting target snapshot-list from {0}".format(args.ssh_target))
@@ -483,21 +617,34 @@ def zfs_autobackup():
             if target_filesystem in target_snapshots and target_snapshots[target_filesystem]:
                 #incremental mode, determine what to send and what is obsolete
 
-                #latest succesfully send snapshot, should be common on both source and target
+                #latest succesfully sent snapshot, should be common on both source and target (at least a bookmark on source)
                 latest_target_snapshot=target_snapshots[target_filesystem][-1]
 
-                if latest_target_snapshot not in source_snapshots[source_filesystem]:
+                #find our starting snapshot/bookmark:
+                latest_target_bookmark='#'+latest_target_snapshot[1:]
+                if latest_target_snapshot in source_snapshots[source_filesystem]:
+                    latest_source_index=source_snapshots[source_filesystem].index(latest_target_snapshot)
+                    source_bookmark=latest_target_snapshot
+                elif latest_target_bookmark in source_snapshots[source_filesystem]:
+                    latest_source_index=source_snapshots[source_filesystem].index(latest_target_bookmark)
+                    source_bookmark=latest_target_bookmark
+                else:
                     #cant find latest target anymore. find first common snapshot and inform user
-                    error="Cant find latest target snapshot on source, did you destroy it accidently? "+source_filesystem+"@"+latest_target_snapshot
+                    error_msg="Cant find latest target snapshot or bookmark on source, did you destroy/rename it?"
+                    error_msg=error_msg+"\nLatest on target : "+target_filesystem+latest_target_snapshot
+                    error_msg=error_msg+"\nMissing on source: "+source_filesystem+latest_target_bookmark
+                    found=False
                     for latest_target_snapshot in reversed(target_snapshots[target_filesystem]):
                         if latest_target_snapshot in source_snapshots[source_filesystem]:
-                            error=error+"\nYou could solve this by rolling back to: "+target_filesystem+"@"+latest_target_snapshot;
+                            error_msg=error_msg+"\nYou could solve this by rolling back to this common snapshot on target: "+target_filesystem+latest_target_snapshot
+                            found=True
                             break
+                    if not found:
+                        error_msg=error_msg+"\nAlso could not find an earlier common snapshot to rollback to."
 
-                    raise(Exception(error))
+                    raise(Exception(error_msg))
 
                 #send all new source snapshots that come AFTER the last target snapshot
-                latest_source_index=source_snapshots[source_filesystem].index(latest_target_snapshot)
                 send_snapshots=source_snapshots[source_filesystem][latest_source_index+1:]
 
                 #source snapshots that come BEFORE last target snapshot are obsolete
@@ -508,6 +655,7 @@ def zfs_autobackup():
                 target_obsolete_snapshots[target_filesystem]=target_snapshots[target_filesystem][0:latest_target_index]
             else:
                 #initial mode, send all snapshots, nothing is obsolete:
+                source_bookmark=None
                 latest_target_snapshot=None
                 send_snapshots=source_snapshots[source_filesystem]
                 target_obsolete_snapshots[target_filesystem]=[]
@@ -519,7 +667,7 @@ def zfs_autobackup():
                 if send_snapshots and args.rollback and latest_target_snapshot:
                     #roll back any changes on target
                     debug("Rolling back target to latest snapshot.")
-                    run(ssh_to=args.ssh_target, test=args.test, cmd=["zfs", "rollback", target_filesystem+"@"+latest_target_snapshot ])
+                    run(ssh_to=args.ssh_target, test=args.test, cmd=["zfs", "rollback", target_filesystem+latest_target_snapshot ])
 
 
                 for send_snapshot in send_snapshots:
@@ -530,19 +678,36 @@ def zfs_autobackup():
                     else:
                         resume_token=None
 
+                    #hold the snapshot we're sending on the source
+                    zfs_hold_snapshot(ssh_to=args.ssh_source, snapshot=source_filesystem+send_snapshot)
+
                     zfs_transfer(
                         ssh_source=args.ssh_source, source_filesystem=source_filesystem,
-                        first_snapshot=latest_target_snapshot, second_snapshot=send_snapshot,
+                        first_snapshot=source_bookmark, second_snapshot=send_snapshot,
                         ssh_target=args.ssh_target, target_filesystem=target_filesystem,
                         resume_token=resume_token
                     )
 
+                    #hold the snapshot we just send on the target
+                    zfs_hold_snapshot(ssh_to=args.ssh_target, snapshot=target_filesystem+send_snapshot)
+
+                    #bookmark the snapshot we just send on the source, so we can also release and mark it obsolete.
+                    zfs_bookmark_snapshot(ssh_to=args.ssh_source, snapshot=source_filesystem+send_snapshot)
+                    zfs_release_snapshot(ssh_to=args.ssh_source, snapshot=source_filesystem+send_snapshot)
+                    source_obsolete_snapshots[source_filesystem].append(send_snapshot)
 
 
-                    #now that we succesfully transferred this snapshot, the previous snapshot is obsolete:
+                    #now that we succesfully transferred this snapshot, cleanup the previous stuff
                     if latest_target_snapshot:
+                        #dont need the latest_target_snapshot anymore
+                        zfs_release_snapshot(ssh_to=args.ssh_target, snapshot=target_filesystem+latest_target_snapshot)
                         target_obsolete_snapshots[target_filesystem].append(latest_target_snapshot)
-                        source_obsolete_snapshots[source_filesystem].append(latest_target_snapshot)
+
+                        #delete previous bookmark
+                        zfs_destroy_bookmark(ssh_to=args.ssh_source, bookmark=source_filesystem+source_bookmark)
+
+                        # zfs_release_snapshot(ssh_to=args.ssh_source, snapshot=source_filesystem+"@"+latest_target_snapshot)
+                        # source_obsolete_snapshots[source_filesystem].append(latest_target_snapshot)
                     #we just received a new filesytem?
                     else:
                         if args.clear_refreservation:
@@ -558,7 +723,7 @@ def zfs_autobackup():
 
 
                     latest_target_snapshot=send_snapshot
-
+                    source_bookmark='#'+latest_target_snapshot[1:]
 
 
     ############## cleanup section
@@ -609,10 +774,9 @@ def zfs_autobackup():
 
 # parse arguments
 import argparse
-parser = argparse.ArgumentParser(description='ZFS autobackup v2.1')
+parser = argparse.ArgumentParser(description='ZFS autobackup v2.2')
 parser.add_argument('--ssh-source', default="local", help='Source host to get backup from. (user@hostname) Default %(default)s.')
 parser.add_argument('--ssh-target', default="local", help='Target host to push backup to. (user@hostname) Default  %(default)s.')
-parser.add_argument('--ssh-cipher', default=None, help='SSH cipher to use (default  %(default)s)')
 parser.add_argument('--keep-source', type=int, default=30, help='Number of days to keep old snapshots on source. Default %(default)s.')
 parser.add_argument('--keep-target', type=int, default=30, help='Number of days to keep old snapshots on target. Default %(default)s.')
 parser.add_argument('backup_name',    help='Name of the backup (you should set the zfs property "autobackup:backup-name" to true on filesystems you want to backup')
@@ -620,18 +784,20 @@ parser.add_argument('target_fs',    help='Target filesystem')
 
 parser.add_argument('--no-snapshot', action='store_true', help='dont create new snapshot (usefull for finishing uncompleted backups, or cleanups)')
 parser.add_argument('--no-send', action='store_true', help='dont send snapshots (usefull to only do a cleanup)')
-parser.add_argument('--resume', action='store_true', help='support resuming of interrupted transfers by using the zfs extensible_dataset feature (both zpools should have it enabled)')
-
+parser.add_argument('--allow-empty', action='store_true', help='if nothing has changed, still create empty snapshots.')
+parser.add_argument('--resume', action='store_true', help='support resuming of interrupted transfers by using the zfs extensible_dataset feature (both zpools should have it enabled) Disadvantage is that you need to use zfs recv -A if another snapshot is created on the target during a receive. Otherwise it will keep failing.')
 parser.add_argument('--strip-path', default=0, type=int, help='number of directory to strip from path (use 1 when cloning zones between 2 SmartOS machines)')
+parser.add_argument('--buffer', default="",  help='Use mbuffer with specified size to speedup zfs transfer. (e.g. --buffer 1G)')
 
 
 parser.add_argument('--destroy-stale', action='store_true', help='Destroy stale backups that have no more snapshots. Be sure to verify the output before using this! ')
 parser.add_argument('--clear-refreservation', action='store_true', help='Set refreservation property to none for new filesystems. Usefull when backupping SmartOS volumes. (recommended)')
 parser.add_argument('--clear-mountpoint', action='store_true', help='Sets canmount=noauto property, to prevent the received filesystem from mounting over existing filesystems. (recommended)')
+parser.add_argument('--filter-properties', action='append', help='Filter properties when receiving filesystems. Can be specified multiple times. (Example: If you send data from Linux to FreeNAS, you should filter xattr)')
 parser.add_argument('--rollback', action='store_true', help='Rollback changes on the target before starting a backup. (normally you can prevent changes by setting the readonly property on the target_fs to on)')
+parser.add_argument('--ignore-transfer-errors', action='store_true', help='Ignore transfer errors (still checks if received filesystem exists. usefull for acltype errors)')
 
 
-parser.add_argument('--compress', action='store_true', help='use compression during zfs send/recv')
 parser.add_argument('--test', action='store_true', help='dont change anything, just show what would be done (still does all read-only operations)')
 parser.add_argument('--verbose', action='store_true', help='verbose output')
 parser.add_argument('--debug', action='store_true', help='debug output (shows commands that are executed)')
@@ -639,5 +805,11 @@ parser.add_argument('--debug', action='store_true', help='debug output (shows co
 #note args is the only global variable we use, since its a global readonly setting anyway
 args = parser.parse_args()
 
-
-zfs_autobackup()
+try:
+    zfs_autobackup()
+except Exception as e:
+    if args.debug:
+        raise
+    else:
+        print("* ABORTED *")
+        print(str(e))