diff --git a/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/api/ImportInfo.java b/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/api/ImportInfo.java
index 92227c1..b66d93a 100644
--- a/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/api/ImportInfo.java
+++ b/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/api/ImportInfo.java
@@ -66,7 +66,9 @@
     /**
      * Marks that the node at {@code path} is missing.
      * @param path the path
+     * @deprecated Is no longer issued, as this depends on the registered node type definitions
      */
+    @Deprecated
     void onMissing(String path);
 
     /**
diff --git a/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/AutoSave.java b/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/AutoSave.java
index 2d526e2..c2bf40b 100644
--- a/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/AutoSave.java
+++ b/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/AutoSave.java
@@ -17,11 +17,10 @@
 
 package org.apache.jackrabbit.vault.fs.io;
 
-import java.util.HashSet;
-import java.util.Set;
-
+import javax.jcr.InvalidItemStateException;
 import javax.jcr.RepositoryException;
 import javax.jcr.Session;
+import javax.jcr.nodetype.ConstraintViolationException;
 
 import org.apache.jackrabbit.vault.fs.spi.ProgressTracker;
 import org.jetbrains.annotations.NotNull;
@@ -55,9 +54,9 @@
     private int threshold = 1024;
 
     /**
-     * set that records the missing mandatory items. save has to be delay until they are resolved
+     * number of modified nodes to wait for a save retry (only set to a value != 0 after failed save).
      */
-    private final Set<String> missingMandatory = new HashSet<String>();
+    private int failedSaveThreshold = 0;
 
     /**
      * tracker to use to report progress messages
@@ -93,7 +92,6 @@
         ret.lastSave = lastSave;
         ret.tracker = tracker;
         ret.dryRun = dryRun;
-        ret.missingMandatory.addAll(missingMandatory);
         ret.debugFailEach = debugFailEach;
         // don't copy save count, otherwise it will fail for ever.
         // ret.debugSaveCount = debugSaveCount;
@@ -126,12 +124,16 @@
      * @return {@code true} if threshold reached.
      */
     public boolean needsSave() {
-        boolean res = (numModified - lastSave) >= threshold;
-        if (res && !missingMandatory.isEmpty()) {
-            log.debug("Threshold of {} reached but still unresolved mandatory items.", threshold);
-            res = false;
-        }
-        return res;
+        return (numModified - lastSave) >= threshold + failedSaveThreshold;
+    }
+
+    /**
+     * Same as {@link #save(Session, boolean)} with the second argument being {@code true}.
+     * @param session
+     * @throws RepositoryException
+     */
+    public void save(@Nullable Session session) throws RepositoryException {
+        save(session, true);
     }
 
     /**
@@ -139,18 +141,19 @@
      * @param session the session to save. can be {@code null}
      * @throws RepositoryException if an error occurs.
      */
-    public void save(@Nullable Session session) throws RepositoryException {
-        if (threshold == Integer.MAX_VALUE) {
-            log.trace("Save disabled.");
-            return;
-        }
+    public void save(@Nullable Session session, boolean isIntermediate) throws RepositoryException {
         int diff = numModified - lastSave;
-        log.debug("Threshold of {} reached. {} approx {} transient changes. {} unresolved", new Object[]{
-                threshold,
-                dryRun ? "dry run, reverting" : "saving",
-                diff,
-                missingMandatory.size()
-        });
+        if (isIntermediate) {
+            if (threshold == Integer.MAX_VALUE) {
+                log.trace("Intermediate save disabled.");
+                return;
+            }
+            log.debug("Threshold of {} reached. {} approx {} transient changes.", 
+                    threshold,
+                    dryRun ? "dry run, reverting" : "saving",
+                    diff
+            );
+        }
         if (tracker != null) {
             if (dryRun) {
                 tracker.track("reverting approx " + diff + " nodes... (dry run)", "");
@@ -158,6 +161,7 @@
                 tracker.track("saving approx " + diff + " nodes...", "");
             }
         }
+        // TODO: how can session be null here?
         if (session != null) {
             if (debugFailEach > 0 && debugSaveCount > 0 && debugSaveCount%debugFailEach == 0) {
                 String msg = String.format("Debugging provoked failure after %s saves.", debugSaveCount);
@@ -165,21 +169,54 @@
                 throw new RepositoryException(msg);
             }
 
+            if (!saveWithBackoff(session)) {
+                // either retry after some more nodes have been modified or after throttle 
+                // retry with next save() after another 10 nodes have been modified
+                failedSaveThreshold = 10;
+                log.warn("Retry auto-save after {} modified nodes", failedSaveThreshold);
+            }
+        }
+        lastSave = numModified;
+        failedSaveThreshold = 0;
+    }
+
+    /**
+     * 
+     * @param session
+     * @return {@code true} in case was successful or {@code false} in case it failed with a potentially recoverable {@link RepositoryException}
+     * @throws RepositoryException in case of unrecoverable exceptions
+     */
+    private boolean saveWithBackoff(@NotNull Session session) throws RepositoryException {
+        try {
             if (dryRun) {
                 session.refresh(false);
             } else {
                 try {
                     session.save();
-                    debugSaveCount++;
                 } catch (RepositoryException e) {
                     log.error("error during auto save - retrying after refresh...");
                     session.refresh(true);
                     session.save();
-                    debugSaveCount++;
                 }
+                debugSaveCount++;
+            }
+        } catch (RepositoryException e) {
+            if (isPotentiallyTransientException(e)) {
+                log.warn("could not auto-save due to potentially transient exception {}", e.getCause());
+                log.debug("auto save exception", e);
+                return false;
+            } else {
+                throw e;
             }
         }
-        lastSave = numModified;
+        return true;
+    }
+
+    boolean isPotentiallyTransientException(RepositoryException e) {
+        if (e instanceof InvalidItemStateException || e instanceof ConstraintViolationException) {
+            return true;
+        }
+        return false;
     }
 
     /**
@@ -208,16 +245,25 @@
         return needsSave();
     }
 
+    /**
+     * As not working reliably it is simply ignored.
+     * @param path
+     */
+    @Deprecated
     public void markMissing(@NotNull String path) {
-        missingMandatory.add(path);
     }
 
+    /**
+     * As not working reliably it is simply ignored.
+     * @param path
+     */
+    @Deprecated
     public void markResolved(@NotNull String path) {
-        missingMandatory.remove(path);
     }
 
     @Override
     public String toString() {
         return String.valueOf(threshold);
     }
+
 }
diff --git a/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/Importer.java b/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/Importer.java
index e94d8b1..2e4f533 100644
--- a/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/Importer.java
+++ b/vault-core/src/main/java/org/apache/jackrabbit/vault/fs/io/Importer.java
@@ -460,7 +460,7 @@
         while (recoveryRetryCounter++ < 10) {
             try {
                 commit(session, root, skipList);
-                autoSave.save(session);
+                autoSave.save(session, false);
                 break;
             } catch (RepositoryException e) {
                 if (recoveryRetryCounter == 10) {
@@ -834,7 +834,7 @@
             }
 
             if (autoSave.needsSave()) {
-                autoSave.save(session);
+                autoSave.save(session, false);
                 // save checkpoint
                 cpTxInfo = info;
                 cpAutosave = autoSave.copy();
@@ -988,27 +988,21 @@
                 switch (type) {
                     case CRE:
                         track("A", path);
-                        autoSave.markResolved(path);
                         break;
                     case DEL:
                         track("D", path);
-                        autoSave.markResolved(path);
                         break;
                     case MOD:
                         track("U", path);
-                        autoSave.markResolved(path);
                         break;
                     case NOP:
                         track("-", path);
-                        autoSave.markResolved(path);
                         break;
                     case REP:
                         track("R", path);
-                        autoSave.markResolved(path);
                         break;
                     case MIS:
                         track("!", path);
-                        autoSave.markMissing(path);
                         break;
                     case ERR:
                         Exception error = entry.getValue().getError();
diff --git a/vault-core/src/main/java/org/apache/jackrabbit/vault/util/RepositoryCopier.java b/vault-core/src/main/java/org/apache/jackrabbit/vault/util/RepositoryCopier.java
index 6f57b2b..bff161e 100644
--- a/vault-core/src/main/java/org/apache/jackrabbit/vault/util/RepositoryCopier.java
+++ b/vault-core/src/main/java/org/apache/jackrabbit/vault/util/RepositoryCopier.java
@@ -39,6 +39,8 @@
 import org.apache.jackrabbit.vault.fs.api.ProgressTrackerListener;
 import org.apache.jackrabbit.vault.fs.api.RepositoryAddress;
 import org.apache.jackrabbit.vault.fs.api.WorkspaceFilter;
+import org.apache.jackrabbit.vault.fs.io.AutoSave;
+import org.apache.jackrabbit.vault.fs.spi.ProgressTracker;
 import org.apache.jackrabbit.util.Text;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -264,17 +266,21 @@
         currentSize = 0;
         totalSize = 0;
         start = System.currentTimeMillis();
-        copy(srcRoot, dstRoot, dstName, recursive);
+        
+        AutoSave autoSave = new AutoSave();
+        autoSave.setThreshold(getBatchSize());
+        autoSave.setTracker(new ProgressTracker(tracker));
+        copy(autoSave, srcRoot, dstRoot, dstName, recursive);
         if (numNodes > 0) {
             track("", "Saving %d nodes...", numNodes);
-            dstSession.save();
+            autoSave.save(dstSession, false);
             track("", "Done.");
         }
         long end = System.currentTimeMillis();
         track("", "Copy completed. %d nodes in %dms. %d bytes", totalNodes, end-start, totalSize);
     }
 
-    private void copy(Node src, Node dstParent, String dstName, boolean recursive)
+    private void copy(AutoSave autoSave, Node src, Node dstParent, String dstName, boolean recursive)
             throws RepositoryException {
         if (abort) {
             return;
@@ -440,7 +446,7 @@
                     Node child = niter.nextNode();
                     String cName = checkNameSpace(child.getName(), src.getSession(), dst.getSession());
                     names.remove(cName);
-                    copy(child, dst, cName, true);
+                    copy(autoSave, child, dst, cName, true);
                 }
                 if (resumeFrom == null) {
                     // check if we need to order
@@ -471,30 +477,27 @@
 
         if (!skip) {
             numNodes++;
+            autoSave.modified(1);
         }
 
         // check for save
-        if (numNodes >= batchSize) {
-            try {
-                track("", "Intermediate saving %d nodes (%d kB)...", numNodes, currentSize/1000);
-                long now = System.currentTimeMillis();
-                dst.getSession().save();
-                long end = System.currentTimeMillis();
-                track("", "Done in %d ms. Total time: %d, total nodes %d, %d kB", end-now, end-start, totalNodes, totalSize/1000);
-                lastKnownGood = currentPath;
-                numNodes = 0;
-                currentSize = 0;
-                if (throttle > 0) {
-                    track("", "Throttling enabled. Waiting %d second%s...", throttle, throttle == 1 ? "" : "s");
-                    try {
-                        Thread.sleep(throttle * 1000);
-                    } catch (InterruptedException e) {
-                        log.warn("Interrupted while waiting", e);
-                        Thread.currentThread().interrupt();
-                    }
+        if (autoSave.needsSave()) {
+            track("", "Intermediate saving %d nodes (%d kB)...", numNodes, currentSize/1000);
+            long now = System.currentTimeMillis();
+            autoSave.save(dst.getSession(), true);
+            long end = System.currentTimeMillis();
+            track("", "Done in %d ms. Total time: %d, total nodes %d, %d kB", end-now, end-start, totalNodes, totalSize/1000);
+            lastKnownGood = currentPath;
+            numNodes = 0;
+            currentSize = 0;
+            if (throttle > 0) {
+                track("", "Throttling enabled. Waiting %d second%s...", throttle, throttle == 1 ? "" : "s");
+                try {
+                    Thread.sleep(throttle * 1000);
+                } catch (InterruptedException e) {
+                    log.warn("Interrupted while waiting", e);
+                    Thread.currentThread().interrupt();
                 }
-            } catch (RepositoryException e) {
-                log.error("Error during intermediate save ({}); try again later: {}", numNodes, e.toString());
             }
         }
     }