diff --git a/pom.xml b/pom.xml
index b48b84f0a..5794ef006 100755
--- a/pom.xml
+++ b/pom.xml
@@ -101,6 +101,18 @@
             <version>1.1.6</version>
         </dependency>
 
+        <dependency>
+            <groupId>net.java.dev.jna</groupId>
+            <artifactId>jna</artifactId>
+            <version>4.2.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>net.java.dev.jna</groupId>
+            <artifactId>jna-platform</artifactId>
+            <version>4.2.1</version>
+        </dependency>
+
         <!-- optional dependencies -->
 
         <dependency>
diff --git a/src/main/java/net/openhft/chronicle/hash/impl/PosixMsync.java b/src/main/java/net/openhft/chronicle/hash/impl/PosixMsync.java
new file mode 100644
index 000000000..e36013ae0
--- /dev/null
+++ b/src/main/java/net/openhft/chronicle/hash/impl/PosixMsync.java
@@ -0,0 +1,42 @@
+/*
+ *      Copyright (C) 2015  higherfrequencytrading.com
+ *
+ *      This program is free software: you can redistribute it and/or modify
+ *      it under the terms of the GNU Lesser General Public License as published by
+ *      the Free Software Foundation, either version 3 of the License.
+ *
+ *      This program is distributed in the hope that it will be useful,
+ *      but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *      GNU Lesser General Public License for more details.
+ *
+ *      You should have received a copy of the GNU Lesser General Public License
+ *      along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.openhft.chronicle.hash.impl;
+
+import com.sun.jna.Native;
+import com.sun.jna.Platform;
+
+import java.io.IOException;
+
+final class PosixMsync {
+
+    private static final int MS_SYNC = 4;
+
+    public static void msync(long addr, long length) throws IOException {
+        if (msync(addr, length, MS_SYNC) == -1)
+            throw new IOException(strerror_r(Native.getLastError(), null, 0));
+    }
+
+    private static native String strerror_r(int errnum, char[] buf, int buflen);
+
+    private static native int msync(long addr, long length, int flags);
+
+    static {
+        Native.register(PosixMsync.class, Platform.C_LIBRARY_NAME);
+    }
+
+    private PosixMsync() {}
+}
diff --git a/src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java b/src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java
index d7b096546..65d47a13c 100644
--- a/src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java
+++ b/src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java
@@ -731,10 +731,24 @@ public abstract class VanillaChronicleHash<K,
     }
 
     private void allocateTierBulk() {
+        try {
+            RandomAccessFile raf = persisted() ? new RandomAccessFile(file, "rw") : null;
+            try {
+                allocateTierBulk0(raf);
+            } finally {
+                if (raf != null)
+                    raf.close();
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void allocateTierBulk0(RandomAccessFile raf) throws IOException {
         int allocatedExtraTierBulks = globalMutableState.getAllocatedExtraTierBulks();
-        mapTierBulks(allocatedExtraTierBulks);
+
+        mapTierBulks(raf, allocatedExtraTierBulks);
 
-        // integer overflow aware
         long firstTierIndex = extraTierIndexToTierIndex(allocatedExtraTierBulks * tiersInBulk);
         BytesStore tierBytesStore = tierBytesStore(firstTierIndex);
         long firstTierOffset = tierBytesOffset(firstTierIndex);
@@ -746,13 +760,30 @@ public abstract class VanillaChronicleHash<K,
         long lastTierIndex = firstTierIndex + tiersInBulk - 1;
         linkAndZeroOutFreeTiers(firstTierIndex, lastTierIndex);
 
-        // TODO HCOLL-397 insert msync here!
+        if (persisted()) {
+            long address = tierBytesStore.address(firstTierOffset - tierBulkInnerOffsetToTiers);
+            // address should be a multiple of page size
+            if (OS.pageAlign(address) != address) {
+                address = OS.pageAlign(address) - OS.pageSize();
+            }
+            long endAddress = tierBytesStore.address(tierBytesOffset(lastTierIndex)) + tierSize;
+            long length = endAddress - address;
+            msync(raf, address, length);
+        }
 
         // after we are sure the new bulk is initialized, update the global mutable state
         globalMutableState.setAllocatedExtraTierBulks(allocatedExtraTierBulks + 1);
         globalMutableState.setFirstFreeTierIndex(firstTierIndex);
     }
 
+    private static void msync(RandomAccessFile raf, long address, long length) throws IOException {
+        if (OS.isWindows()) {
+            WindowsMsync.msync(raf, address, length);
+        } else {
+            PosixMsync.msync(address, length);
+        }
+    }
+
     public void linkAndZeroOutFreeTiers(long firstTierIndex, long lastTierIndex) {
         for (long tierIndex = firstTierIndex; tierIndex <= lastTierIndex; tierIndex++) {
             long tierOffset = tierBytesOffset(tierIndex);
@@ -822,9 +853,23 @@ public abstract class VanillaChronicleHash<K,
     }
 
     private void mapTierBulks(int upToBulkIndex) {
+        try {
+            RandomAccessFile raf = persisted() ? new RandomAccessFile(file, "rw") : null;
+            try {
+                mapTierBulks(raf, upToBulkIndex);
+            } finally {
+                if (raf != null)
+                    raf.close();
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void mapTierBulks(RandomAccessFile raf, int upToBulkIndex) {
         if (persisted()) {
             try {
-                mapTierBulksMapped(upToBulkIndex);
+                mapTierBulksMapped(raf, upToBulkIndex);
             } catch (IOException e) {
                 throw new RuntimeException(e);
             }
@@ -834,7 +879,7 @@ public abstract class VanillaChronicleHash<K,
         }
     }
 
-    private void mapTierBulksMapped(int upToBulkIndex) throws IOException {
+    private void mapTierBulksMapped(RandomAccessFile raf, int upToBulkIndex) throws IOException {
         int firstBulkToMapIndex = tierBulkOffsets.size();
         int bulksToMap = upToBulkIndex + 1 - firstBulkToMapIndex;
         long mapSize = bulksToMap * tierBulkSizeInBytes;
@@ -852,14 +897,11 @@ public abstract class VanillaChronicleHash<K,
             // Now might need to have bigger mapSize
             mapSize += firstBulkToMapOffsetWithinMapping;
         }
-        // TODO optimize -- create a file channel not on each tier bulk creation
-        try (RandomAccessFile raf = new RandomAccessFile(file, "rw")) {
-            // mapping by hand, because MappedFile/MappedBytesStore doesn't allow to create a BS
-            // which starts not from the beginning of the file, but has start() of 0
-            NativeBytesStore extraStore = map(raf, mapSize, mappingOffsetInFile);
-            appendBulkData(firstBulkToMapIndex, upToBulkIndex, extraStore,
-                    firstBulkToMapOffsetWithinMapping);
-        }
+        // mapping by hand, because MappedFile/MappedBytesStore doesn't allow to create a BS
+        // which starts not from the beginning of the file, but has start() of 0
+        NativeBytesStore extraStore = map(raf, mapSize, mappingOffsetInFile);
+        appendBulkData(firstBulkToMapIndex, upToBulkIndex, extraStore,
+                firstBulkToMapOffsetWithinMapping);
     }
 
     /**
diff --git a/src/main/java/net/openhft/chronicle/hash/impl/WindowsMsync.java b/src/main/java/net/openhft/chronicle/hash/impl/WindowsMsync.java
new file mode 100644
index 000000000..b5f97d873
--- /dev/null
+++ b/src/main/java/net/openhft/chronicle/hash/impl/WindowsMsync.java
@@ -0,0 +1,61 @@
+/*
+ *      Copyright (C) 2015  higherfrequencytrading.com
+ *
+ *      This program is free software: you can redistribute it and/or modify
+ *      it under the terms of the GNU Lesser General Public License as published by
+ *      the Free Software Foundation, either version 3 of the License.
+ *
+ *      This program is distributed in the hope that it will be useful,
+ *      but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *      GNU Lesser General Public License for more details.
+ *
+ *      You should have received a copy of the GNU Lesser General Public License
+ *      along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.openhft.chronicle.hash.impl;
+
+import com.sun.jna.Native;
+import com.sun.jna.platform.win32.Kernel32Util;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
+import static com.sun.jna.platform.win32.WinError.ERROR_LOCK_VIOLATION;
+
+final class WindowsMsync {
+
+    public static void msync(RandomAccessFile raf, long addr, long length)
+            throws IOException {
+        int retry = 0;
+        boolean success;
+        int lastError = 0;
+        // FlushViewOfFile can fail with ERROR_LOCK_VIOLATION if the memory system is writing dirty
+        // pages to disk. As there is no way to synchronize the flushing then we retry a limited
+        // number of times.
+        do {
+            if ((success = FlushViewOfFile(addr, length)) ||
+                    (lastError = GetLastError()) != ERROR_LOCK_VIOLATION)
+                break;
+            retry++;
+        } while (retry < 3);
+
+        if (success) {
+            // Finally calls FlushFileBuffers
+            raf.getChannel().force(false);
+        } else {
+            throw new IOException(Kernel32Util.formatMessage(lastError));
+        }
+    }
+
+    private static native boolean FlushViewOfFile(long addr, long length);
+
+    private static native int GetLastError();
+
+    static {
+        Native.register(WindowsMsync.class, "kernel32");
+    }
+
+    private WindowsMsync() {}
+}