diff --git a/devstack-vm-gate-dev.sh b/devstack-vm-gate-dev.sh
index 0625e0ae..fdb08a62 100755
--- a/devstack-vm-gate-dev.sh
+++ b/devstack-vm-gate-dev.sh
@@ -11,13 +11,19 @@ export SKIP_DEVSTACK_GATE_PROJECT=1
 export DEVSTACK_GATE_TEMPEST=1
 export ZUUL_BRANCH=master
 export ZUUL_PROJECT=testing
+export ZUUL_REF=refs/zuul/Ztest
 export JOB_NAME=test
 export BUILD_NUMBER=42
 export GERRIT_CHANGE_NUMBER=1234
 export GERRIT_PATCHSET_NUMBER=1
+export DEVSTACK_GATE_TEMPEST=${DEVSTACK_GATE_TEMPEST:-0}
+export DEVSTACK_GATE_CINDER=${DEVSTACK_GATE_CINDER:-0}
+export DEVSTACK_GATE_QUANTUM=${DEVSTACK_GATE_QUANTUM:-0}
+export DEVSTACK_GATE_GRENADE=${DEVSTACK_GATE_GRENADE:-""}
 EOF
 
-rsync -az --delete $WORKSPACE/ jenkins@$NODE_IP_ADDR:workspace/
+rsync -az $WORKSPACE/ jenkins@$NODE_IP_ADDR:workspace-cache/
+rsync -az $WORKSPACE/ jenkins@$NODE_IP_ADDR:workspace/
 RETVAL=$?
 if [ $RETVAL != 0 ]; then
     exit $RETVAL
diff --git a/devstack-vm-gate-wrap.sh b/devstack-vm-gate-wrap.sh
index c71b1cb6..f85ea89b 100755
--- a/devstack-vm-gate-wrap.sh
+++ b/devstack-vm-gate-wrap.sh
@@ -40,6 +40,9 @@ export DEVSTACK_CINDER_SECURE_DELETE=${DEVSTACK_CINDER_SECURE_DELETE:-0}
 # Only applicable to master branch
 export DEVSTACK_GATE_QUANTUM=${DEVSTACK_GATE_QUANTUM:-0}
 
+# Set to the name of the "old" branch to run grenade (eg "stable/folsom")
+export DEVSTACK_GATE_GRENADE=${DEVSTACK_GATE_GRENADE:-""}
+
 # Set the virtualization driver to: libvirt, openvz
 export DEVSTACK_GATE_VIRT_DRIVER=${DEVSTACK_GATE_VIRT_DRIVER:-libvirt}
 
@@ -56,12 +59,13 @@ if [ -z "$SKIP_DEVSTACK_GATE_PROJECT" ]; then
     PROJECTS="openstack-ci/devstack-gate $PROJECTS"
 fi
 
-export DEST=/opt/stack
+export BASE=/opt/stack
 
 # Most of the work of this script is done in functions so that we may
 # easily redirect their stdout / stderr to log files.
 
 function setup_workspace {
+    DEST=$1
     # Enabled detailed logging, since output of this function is redirected
     set -o xtrace
 
@@ -75,6 +79,21 @@ function setup_workspace {
       sudo bash -c 'echo "127.0.1.1 $HOSTNAME" >>/etc/hosts'
     fi
 
+    # Hpcloud provides no swap, but does have a virtual disk mounted
+    # at /mnt we can use.  It also doesn't have enough space on / for
+    # two devstack installs, so we partition the vdisk:
+    if [ `grep SwapTotal /proc/meminfo | awk '{ print $2; }'` -eq 0 ] && \
+       [ -b /dev/vdb ]; then
+      sudo umount /dev/vdb
+      sudo parted /dev/vdb --script -- mklabel msdos
+      sudo parted /dev/vdb --script -- mkpart primary linux-swap 0 8192
+      sudo parted /dev/vdb --script -- mkpart primary ext2 8192 -1
+      sudo mkswap /dev/vdb1
+      sudo mkfs.ext4 /dev/vdb2
+      sudo swapon /dev/vdb1
+      sudo mount /dev/vdb2 /opt
+    fi
+
     sudo mkdir -p $DEST
     sudo chown -R jenkins:jenkins $DEST
     cd $DEST
@@ -82,9 +101,10 @@ function setup_workspace {
     # The vm template update job should cache the git repos
     # Move them to where we expect:
     if ls ~/workspace-cache/*; then
-      mv ~/workspace-cache/* $DEST
+      rsync -a ~/workspace-cache/ $DEST/
     fi
 
+    echo "Using branch: $ZUUL_BRANCH"
     for PROJECT in $PROJECTS
     do
       echo "Setting up $PROJECT"
@@ -142,9 +162,11 @@ function setup_workspace {
       cd $DEST
     done
 
-    # Set GATE_SCRIPT_DIR to point to devstack-gate in the workspace so that
-    # we are testing the proposed change from this point forward.
-    GATE_SCRIPT_DIR=$DEST/devstack-gate
+    # The vm template update job should cache some images in ~/files.
+    # Move them to where devstack expects:
+    if [ -e ~/cache/files/* ]; then
+      rsync -a ~/cache/files/ $DEST/devstack/files/
+    fi
 
     # Disable detailed logging as we return to the main script
     set +o xtrace
@@ -157,20 +179,6 @@ function setup_host {
     # Make sure headers for the currently running kernel are installed:
     sudo apt-get install -y --force-yes linux-headers-`uname -r`
 
-    # Hpcloud provides no swap, but does have a partition mounted at /mnt
-    # we can use:
-    if [ `cat /proc/meminfo | grep SwapTotal | awk '{ print $2; }'` -eq 0 ] && [ -b /dev/vdb ]; then
-      sudo umount /dev/vdb
-      sudo mkswap /dev/vdb
-      sudo swapon /dev/vdb
-    fi
-
-    # The vm template update job should cache some images in ~/files.
-    # Move them to where devstack expects:
-    if ls ~/cache/files/*; then
-      mv ~/cache/files/* $DEST/devstack/files
-    fi
-
     # Move the PIP cache into position:
     sudo mkdir -p /var/cache/pip
     sudo mv ~/cache/pip/* /var/cache/pip
@@ -191,7 +199,7 @@ function setup_host {
 
     # Create a stack user for devstack to run as, so that we can
     # revoke sudo permissions from that user when appropriate.
-    sudo useradd -U -s /bin/bash -d $DEST -m stack
+    sudo useradd -U -s /bin/bash -d $BASE/new -m stack
     TEMPFILE=`mktemp`
     echo "stack ALL=(root) NOPASSWD:ALL" >$TEMPFILE
     chmod 0440 $TEMPFILE
@@ -216,11 +224,23 @@ function cleanup_host {
 
     sudo cp /var/log/syslog $WORKSPACE/logs/syslog.txt
     sudo cp /var/log/kern.log $WORKSPACE/logs/kern_log.txt
-    sudo cp $DEST/screen-logs/* $WORKSPACE/logs/
-    sudo cp $DEST/devstacklog.txt $WORKSPACE/logs/
 
-    # Make the devstack localrc available with the logs
-    sudo cp $DEST/devstack/localrc $WORKSPACE/logs/localrc.txt
+    if [ -d $BASE/old ]; then
+      mkdir -p $WORKSPACE/logs/old/
+      mkdir -p $WORKSPACE/logs/new/
+      mkdir -p $WORKSPACE/logs/grenade/
+      sudo cp $BASE/old/screen-logs/* $WORKSPACE/logs/old/
+      sudo cp $BASE/old/devstacklog.txt $WORKSPACE/logs/old/
+      sudo cp $BASE/old/devstack/localrc $WORKSPACE/logs/old/localrc.txt
+      sudo cp $BASE/logs/* $WORKSPACE/logs/
+      sudo cp $BASE/new/grenade/localrc $WORKSPACE/logs/grenade/localrc.txt
+      NEWLOGTARGET=$WORKSPACE/logs/new
+    else
+      NEWLOGTARGET=$WORKSPACE/logs
+    fi
+    sudo cp $BASE/new/screen-logs/* $NEWLOGTARGET/
+    sudo cp $BASE/new/devstacklog.txt $NEWLOGTARGET/
+    sudo cp $BASE/new/devstack/localrc $NEWLOGTARGET/localrc.txt
 
     # Make sure jenkins can read all the logs
     sudo chown -R jenkins:jenkins $WORKSPACE/logs/
@@ -232,7 +252,7 @@ function cleanup_host {
     rm $WORKSPACE/logs/*.*.txt
 
     # Save the tempest nosetests results
-    sudo cp $DEST/tempest/nosetests*.xml $WORKSPACE/
+    sudo cp $BASE/new/tempest/nosetests*.xml $WORKSPACE/
     sudo chown jenkins:jenkins $WORKSPACE/nosetests*.xml
     sudo chmod a+r $WORKSPACE/nosetests*.xml
 
@@ -241,10 +261,15 @@ function cleanup_host {
 }
 
 # Make a directory to store logs
+rm -rf logs
 mkdir -p logs
-rm -f logs/*
 
-setup_workspace &> $WORKSPACE/logs/devstack-gate-setup-workspace.txt
+setup_workspace $BASE/new &> \
+  $WORKSPACE/logs/devstack-gate-setup-workspace-new.txt
+
+# Set GATE_SCRIPT_DIR to point to devstack-gate in the workspace so that
+# we are testing the proposed change from this point forward.
+GATE_SCRIPT_DIR=$BASE/new/devstack-gate
 
 # Also, if we're testing devstack-gate, re-exec this script once so
 # that we can test the new version of it.
@@ -254,6 +279,14 @@ if [[ $ZUUL_PROJECT == "openstack-ci/devstack-gate" ]] && [[ $RE_EXEC != "true"
     exec $GATE_SCRIPT_DIR/devstack-vm-gate-wrap.sh
 fi
 
+if [ "$DEVSTACK_GATE_GRENADE" ]; then
+  ORIGBRANCH=$ZUUL_BRANCH
+  ZUUL_BRANCH=$DEVSTACK_GATE_GRENADE
+  setup_workspace $BASE/old &> \
+    $WORKSPACE/logs/devstack-gate-setup-workspace-old.txt
+  ZUUL_BRANCH=$ORIGBRANCH
+fi
+
 echo "Triggered by: https://review.openstack.org/$ZUUL_CHANGE patchset $ZUUL_PATCHSET"
 echo "Pipeline: $ZUUL_PIPELINE"
 
diff --git a/devstack-vm-gate.sh b/devstack-vm-gate.sh
index a811cc3d..70f9e7f5 100755
--- a/devstack-vm-gate.sh
+++ b/devstack-vm-gate.sh
@@ -21,7 +21,7 @@
 
 set -o errexit
 
-cd $DEST/devstack
+cd $BASE/new/devstack
 
 rm -f localrc
 
@@ -62,6 +62,7 @@ EOF
 fi
 
 cat <<EOF >>localrc
+DEST=$BASE/new
 ACTIVE_TIMEOUT=60
 BOOT_TIMEOUT=90
 ASSOCIATE_TIMEOUT=60
@@ -78,8 +79,8 @@ ENABLED_SERVICES=$ENABLED_SERVICES
 SKIP_EXERCISES=$SKIP_EXERCISES
 SERVICE_HOST=127.0.0.1
 SYSLOG=True
-SCREEN_LOGDIR=$DEST/screen-logs
-LOGFILE=$DEST/devstacklog.txt
+SCREEN_LOGDIR=$BASE/new/screen-logs
+LOGFILE=$BASE/new/devstacklog.txt
 VERBOSE=True
 FIXED_RANGE=10.1.0.0/24
 FIXED_NETWORK_SIZE=256
@@ -124,21 +125,42 @@ if [ "$DEVSTACK_GATE_TEMPEST" -eq "1" ]; then
 fi
 
 # Make the workspace owned by the stack user
-sudo chown -R stack:stack $DEST
+sudo chown -R stack:stack $BASE/new
+if [ -d $BASE/old ]; then
+    sed -e 's|$BASE/new|$BASE/old|' < $BASE/new/devstack/localrc \
+      > $BASE/old/devstack/localrc
+    sed -e 's|$BASE/new|$BASE/old|' < $BASE/new/devstack/exerciserc \
+      > $BASE/old/devstack/exerciserc
 
-echo "Running devstack"
-sudo -H -u stack ./stack.sh
+    sudo chown -R stack:stack $BASE/old
+fi
 
-echo "Removing sudo privileges for devstack user"
-sudo rm /etc/sudoers.d/50_stack_sh
+if [ "$DEVSTACK_GATE_GRENADE" != "" ]; then
+    sudo echo "GRENADE_PHASE=work"  >>$BASE/old/devstack/localrc
+    sudo echo "GRENADE_PHASE=trunk" >>$BASE/new/devstack/localrc
+    cat <<EOF >$BASE/new/grenade/localrc
+WORK_DEVSTACK_DIR=$BASE/old/devstack
+TRUNK_DEVSTACK_DIR=$BASE/new/devstack
+EOF
 
-echo "Running devstack exercises"
-sudo -H -u stack ./exercise.sh
+    cd $BASE
+    sudo -H -u stack ./grenade.sh
+else
+    echo "Running devstack"
+    sudo -H -u stack ./stack.sh
+
+    echo "Removing sudo privileges for devstack user"
+    sudo rm /etc/sudoers.d/50_stack_sh
+
+    echo "Running devstack exercises"
+    sudo -H -u stack ./exercise.sh
+fi
 
 if [ "$DEVSTACK_GATE_TEMPEST" -eq "1" ]; then
     echo "Configuring tempest"
+    cd $BASE/new/devstack
     sudo -H -u stack ./tools/configure_tempest.sh
-    cd $DEST/tempest
+    cd $BASE/new/tempest
     echo "Running tempest smoke tests"
     sudo -H -u stack NOSE_XUNIT_FILE=nosetests-smoke.xml nosetests --with-xunit -sv --nologcapture --attr=type=smoke tempest
     RETVAL=$?