diff --git a/.gitignore b/.gitignore
index d1b248ee..31c3f033 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@
 .testrepository
 bin
 *.sw[nop]
+.idea
 *.pyc
diff --git a/actions.yaml b/actions.yaml
new file mode 100644
index 00000000..be586451
--- /dev/null
+++ b/actions.yaml
@@ -0,0 +1,12 @@
+replace-osd:
+  description: Replace a failed osd with a fresh disk
+  params:
+    osd-number:
+      type: integer
+      description: The osd number to operate on.  Example 99.  Hint you can get this information from `ceph osd tree`.
+    replacement-device:
+      type: string
+      description: The replacement device to use. Example /dev/sdb.
+  required: [osd-number, replacement-device]
+  additionalProperties: false
+
diff --git a/actions/__init__.py b/actions/__init__.py
new file mode 100644
index 00000000..ff2381cc
--- /dev/null
+++ b/actions/__init__.py
@@ -0,0 +1,3 @@
+__author__ = 'chris'
+import sys
+sys.path.append('hooks')
diff --git a/actions/replace-osd b/actions/replace-osd
new file mode 120000
index 00000000..d9f1a694
--- /dev/null
+++ b/actions/replace-osd
@@ -0,0 +1 @@
+replace_osd.py
\ No newline at end of file
diff --git a/actions/replace_osd.py b/actions/replace_osd.py
new file mode 100755
index 00000000..fd4264f4
--- /dev/null
+++ b/actions/replace_osd.py
@@ -0,0 +1,84 @@
+#!/usr/bin/python
+
+from charmhelpers.core.hookenv import action_get, log, config, action_fail
+
+__author__ = 'chris'
+
+import os
+import sys
+
+sys.path.append('hooks')
+
+import ceph
+
+"""
+Given a OSD number this script will attempt to turn that back into a mount
+point and then replace the OSD with a new one.
+"""
+
+
+def get_disk_stats():
+    try:
+        # https://www.kernel.org/doc/Documentation/iostats.txt
+        with open('/proc/diskstats', 'r') as diskstats:
+            return diskstats.readlines()
+    except IOError as err:
+        log('Could not open /proc/diskstats.  Error: {}'.format(err.message))
+        action_fail('replace-osd failed because /proc/diskstats could not '
+                    'be opened {}'.format(err.message))
+        return None
+
+
+def lookup_device_name(major_number, minor_number):
+    """
+
+    :param major_number: int.  The major device number
+    :param minor_number: int. The minor device number
+    :return: string.  The name of the device.  Example: /dev/sda.
+    Returns None on error.
+    """
+    diskstats = get_disk_stats()
+    for line in diskstats:
+        parts = line.split()
+        if not len(parts) > 3:
+            # Skip bogus lines
+            continue
+        try:
+            if int(parts[0]) is major_number and int(parts[1]) is \
+                    minor_number:
+                # Found our device.  Return its name
+                return parts[2]
+        except ValueError as value_err:
+            log('Could not convert {} or {} into an integer. Error: {}'
+                .format(parts[0], parts[1], value_err.message))
+            continue
+    return None
+
+
+def get_device_number(osd_number):
+    """
+    This function will return a tuple of (major_number, minor_number)
+    device number for the given osd.
+    :param osd_number: int
+    :rtype : (major_number,minor_number)
+    """
+    path = "/var/lib/ceph/osd/ceph-{}".format(osd_number)
+    info = os.lstat(path)
+    major_number = os.major(info.st_dev)
+    minor_number = os.minor(info.st_dev)
+    return major_number, minor_number
+
+
+if __name__ == '__main__':
+    dead_osd_number = action_get("osd-number")
+    replacement_device = action_get("replacement-device")
+    major, minor = get_device_number(dead_osd_number)
+    device_name = lookup_device_name(major, minor)
+    osd_format = config('osd-format')
+    osd_journal = config('osd-journal')
+
+    ceph.replace_osd(dead_osd_number=dead_osd_number,
+                     dead_osd_device="/dev/{}".format(device_name),
+                     new_osd_device=replacement_device,
+                     osd_format=osd_format,
+                     osd_journal=osd_journal)
diff --git a/hooks/ceph.py b/hooks/ceph.py
index 40e33597..51b06ac8 100644
--- a/hooks/ceph.py
+++ b/hooks/ceph.py
@@ -1,4 +1,3 @@
-
 #
 # Copyright 2012 Canonical Ltd.
 #
@@ -6,19 +5,24 @@
 #  James Page <james.page@canonical.com>
 #  Paul Collins <paul.collins@canonical.com>
 #
-
+import ctypes
+import ctypes.util
+import errno
 import json
 import subprocess
 import time
 import os
 import re
 import sys
+import shutil
+from charmhelpers.cli.host import mounts
 from charmhelpers.core.host import (
     mkdir,
     chownr,
     service_restart,
     cmp_pkgrevno,
-    lsb_release
+    lsb_release,
+    service_stop
 )
 from charmhelpers.core.hookenv import (
     log,
@@ -64,7 +68,7 @@ def get_version():
         pkg = cache[package]
     except:
         # the package is unknown to the current apt cache.
-        e = 'Could not determine version of package with no installation '\
+        e = 'Could not determine version of package with no installation ' \
             'candidate: %s' % package
         error_out(e)
 
@@ -165,6 +169,7 @@ def add_bootstrap_hint(peer):
         # Ignore any errors for this call
         subprocess.call(cmd)
 
+
 DISK_FORMATS = [
     'xfs',
     'ext4',
@@ -178,6 +183,97 @@ CEPH_PARTITIONS = [
 ]
 
 
+def umount(mount_point):
+    """
+    This function unmounts a mounted directory forcibly.  This will
+    be used for unmounting broken hard drive mounts which may hang.
+    If umount returns EBUSY this will lazy unmount.
+    :param mount_point: str.  A String representing the filesystem mount point
+    :return: int.  Returns 0 on success.  errno otherwise.
+    """
+    libc_path = ctypes.util.find_library("c")
+    libc = ctypes.CDLL(libc_path, use_errno=True)
+
+    # First try to umount with MNT_FORCE
+    ret = libc.umount(mount_point, 1)
+    if ret < 0:
+        err = ctypes.get_errno()
+        if err == errno.EBUSY:
+            # Detach from try.  IE lazy umount
+            ret = libc.umount(mount_point, 2)
+            if ret < 0:
+                err = ctypes.get_errno()
+                return err
+            return 0
+        else:
+            return err
+    return 0
+
+
+def replace_osd(dead_osd_number,
+                dead_osd_device,
+                new_osd_device,
+                osd_format,
+                osd_journal,
+                reformat_osd=False,
+                ignore_errors=False):
+    """
+    This function will automate the replacement of a failed osd disk as much
+    as possible. It will revoke the keys for the old osd, remove it from the
+    crush map and then add a new osd into the cluster.
+    :param dead_osd_number: The osd number found in ceph osd tree. Example: 99
+    :param dead_osd_device: The physical device.  Example: /dev/sda
+    :param osd_format:
+    :param osd_journal:
+    :param reformat_osd:
+    :param ignore_errors:
+    """
+    host_mounts = mounts()
+    mount_point = None
+    for mount in host_mounts:
+        if mount[1] == dead_osd_device:
+            mount_point = mount[0]
+    # need to convert dev to osd number
+    # also need to get the mounted drive so we can tell the admin to
+    # replace it
+    try:
+        # Drop this osd out of the cluster. This will begin a
+        # rebalance operation
+        status_set('maintenance', 'Removing osd {}'.format(dead_osd_number))
+        subprocess.check_output(['ceph', 'osd', 'out',
+                                 'osd.{}'.format(dead_osd_number)])
+
+        # Kill the osd process if it's not already dead
+        if systemd():
+            service_stop('ceph-osd@{}'.format(dead_osd_number))
+        else:
+            subprocess.check_output(['stop', 'ceph-osd', 'id={}'.format(
+                dead_osd_number)]),
+        # umount if still mounted
+        ret = umount(mount_point)
+        if ret < 0:
+            raise RuntimeError('umount {} failed with error: {}'.format(
+                mount_point, os.strerror(ret)))
+        # Clean up the old mount point
+        shutil.rmtree(mount_point)
+        subprocess.check_output(['ceph', 'osd', 'crush', 'remove',
+                                 'osd.{}'.format(dead_osd_number)])
+        # Revoke the OSDs access keys
+        subprocess.check_output(['ceph', 'auth', 'del',
+                                 'osd.{}'.format(dead_osd_number)])
+        subprocess.check_output(['ceph', 'osd', 'rm',
+                                 'osd.{}'.format(dead_osd_number)])
+        status_set('maintenance', 'Setting up replacement osd {}'.format(
+            new_osd_device))
+        osdize(new_osd_device,
+               osd_format,
+               osd_journal,
+               reformat_osd,
+               ignore_errors)
+    except subprocess.CalledProcessError as e:
+        log('replace_osd failed with error: ' + e.output)
+
+
 def is_osd_disk(dev):
     try:
         info = subprocess.check_output(['sgdisk', '-i', '1', dev])
diff --git a/tox.ini b/tox.ini
index e8bf7cf9..be053f44 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,7 +18,7 @@ deps = -r{toxinidir}/requirements.txt
 basepython = python2.7
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-commands = flake8 {posargs} hooks unit_tests tests
+commands = flake8 {posargs} actions hooks unit_tests tests
            charm proof
 
 [testenv:venv]
diff --git a/unit_tests/__init__.py b/unit_tests/__init__.py
index f80aab3d..466d7781 100644
--- a/unit_tests/__init__.py
+++ b/unit_tests/__init__.py
@@ -1,2 +1,3 @@
 import sys
 sys.path.append('hooks')
+sys.path.append('actions')
diff --git a/unit_tests/test_replace_osd.py b/unit_tests/test_replace_osd.py
new file mode 100644
index 00000000..827a0ff8
--- /dev/null
+++ b/unit_tests/test_replace_osd.py
@@ -0,0 +1,113 @@
+import errno
+import posix
+
+from mock import call, Mock, patch
+
+import test_utils
+import ceph
+import replace_osd
+
+TO_PATCH = [
+    'ctypes',
+    'status_set',
+]
+
+proc_data = [
+    '   8       0 sda 2291336 263100 108136080 1186276 28844343 28798167 '
+    '2145908072 49433216 0 7550032 50630100\n',
+    '   8       1 sda1 1379 1636 8314 692 75 17 1656 0 0 496 692\n',
+    '   8       2 sda2 1 0 2 0 0 0 0 0 0 0 0\n',
+]
+
+
+def umount_busy(*args):
+    # MNT_FORCE
+    if args[1] == 1:
+        return -1
+    # MNT_DETACH
+    if args[1] == 2:
+        return 0
+
+
+class ReplaceOsdTestCase(test_utils.CharmTestCase):
+    def setUp(self):
+        super(ReplaceOsdTestCase, self).setUp(ceph, TO_PATCH)
+
+    def test_umount_ebusy(self):
+        self.ctypes.util.find_library.return_value = 'libc.so.6'
+        umount_mock = Mock()
+        self.ctypes.CDLL.return_value = umount_mock
+        umount_mock.umount.side_effect = umount_busy
+        self.ctypes.get_errno.return_value = errno.EBUSY
+
+        ret = ceph.umount('/some/osd/mount')
+        umount_mock.assert_has_calls([
+            call.umount('/some/osd/mount', 1),
+            call.umount('/some/osd/mount', 2),
+        ])
+        assert ret == 0
+
+    def test_umount(self):
+        self.ctypes.util.find_library.return_value = 'libc.so.6'
+        umount_mock = Mock()
+        self.ctypes.CDLL.return_value = umount_mock
+        umount_mock.umount.return_value = 0
+
+        ret = ceph.umount('/some/osd/mount')
+        umount_mock.assert_has_calls([
+            call.umount('/some/osd/mount', 1),
+        ])
+        assert ret == 0
+
+    @patch('ceph.mounts')
+    @patch('ceph.subprocess')
+    @patch('ceph.umount')
+    @patch('ceph.osdize')
+    @patch('ceph.shutil')
+    @patch('ceph.systemd')
+    def test_replace_osd(self,
+                         systemd,
+                         shutil,
+                         osdize,
+                         umount,
+                         subprocess,
+                         mounts):
+        mounts.return_value = [['/var/lib/ceph/osd/ceph-a', '/dev/sda']]
+        subprocess.check_output.return_value = True
+        self.status_set.return_value = None
+        systemd.return_value = False
+        umount.return_value = 0
+        osdize.return_value = None
+        shutil.rmtree.return_value = None
+        ceph.replace_osd(dead_osd_number=0,
+                         dead_osd_device='/dev/sda',
+                         new_osd_device='/dev/sdb',
+                         osd_format=True,
+                         osd_journal=None,
+                         reformat_osd=False,
+                         ignore_errors=False)
+        subprocess.check_output.assert_has_calls(
+            [
+                call(['ceph', 'osd', 'out', 'osd.0']),
+                call(['stop', 'ceph-osd', 'id=0']),
+                call(['ceph', 'osd', 'crush', 'remove', 'osd.0']),
+                call(['ceph', 'auth', 'del', 'osd.0']),
+                call(['ceph', 'osd', 'rm', 'osd.0'])
+            ]
+        )
+
+    @patch('replace_osd.get_disk_stats')
+    def test_lookup_device_name(self, disk_stats):
+        disk_stats.return_value = proc_data
+        dev_name = replace_osd.lookup_device_name(major_number=8,
+                                                  minor_number=0)
+        assert dev_name == 'sda', "dev_name: {}".format(dev_name)
+
+    @patch('replace_osd.os.lstat')
+    def test_get_device_number(self, lstat):
+        lstat.return_value = posix.stat_result([
+            16877, 16, 51729L, 3, 0, 0, 217, 0, 1458086872, 1458086872
+        ])
+        major, minor = replace_osd.get_device_number(1)
+        assert major == 202
+        assert minor == 17