diff --git a/docs/contributor/storage/default_csi_plugin.md b/docs/contributor/storage/default_csi_plugin.md
index bd2a838c9e..127e690db8 100644
--- a/docs/contributor/storage/default_csi_plugin.md
+++ b/docs/contributor/storage/default_csi_plugin.md
@@ -161,7 +161,7 @@ spec:
     - sh
     - -c
     - sleep 1d
-    image: nginxinc/nginx-unprivileged:latest
+    image: quay.io/microshift/busybox:1.36
     name: test-container
     securityContext:
       allowPrivilegeEscalation: false
@@ -250,7 +250,7 @@ spec:
     - sh
     - -c
     - sleep 1d
-    image: nginxinc/nginx-unprivileged:latest
+    image: quay.io/microshift/busybox:1.36
     name: test-container
     securityContext:
       allowPrivilegeEscalation: false
diff --git a/test/assets/kustomizations/base/pod-base.yaml b/test/assets/kustomizations/base/pod-base.yaml
index 8e01780051..2b11644349 100644
--- a/test/assets/kustomizations/base/pod-base.yaml
+++ b/test/assets/kustomizations/base/pod-base.yaml
@@ -9,7 +9,7 @@ spec:
       type: RuntimeDefault
   containers:
   - name: test-container
-    image: docker.io/nginxinc/nginx-unprivileged:latest
+    image: quay.io/microshift/busybox:1.36
     securityContext:
       allowPrivilegeEscalation: false
       capabilities:
diff --git a/test/assets/reboot/pod-with-pvc.yaml b/test/assets/reboot/pod-with-pvc.yaml
index 04e160c09f..c5e1ab4c9f 100644
--- a/test/assets/reboot/pod-with-pvc.yaml
+++ b/test/assets/reboot/pod-with-pvc.yaml
@@ -21,7 +21,7 @@ spec:
       type: RuntimeDefault
   containers:
   - name: test-container
-    image: docker.io/nginxinc/nginx-unprivileged:latest
+    image: quay.io/microshift/busybox:1.36
     securityContext:
       allowPrivilegeEscalation: false
       capabilities:
diff --git a/test/bin/ci_phase_boot_and_test.sh b/test/bin/ci_phase_boot_and_test.sh
index a3b10b0dc6..fa8a374b35 100755
--- a/test/bin/ci_phase_boot_and_test.sh
+++ b/test/bin/ci_phase_boot_and_test.sh
@@ -84,13 +84,27 @@ else
     progress=""
 fi
 
+jobs_arg=""
+scenario_action="create-and-run"
+if [[ "${SCENARIO_SOURCES:-}" =~ .*releases.* ]]; then
+    # Release scenarios have grown (e.g. the router scenarios were split
+    # from 1 into 5) and no longer fit if every scenario's VMs stay up for
+    # the whole job. Shut down passed scenarios' VMs as they finish so the
+    # hypervisor only ever holds the still-running scenarios' VMs.
+    export GREENBOOT_TIMEOUT=1200
+    jobs_arg="-j 20"
+    scenario_action="create-run-shutdown"
+fi
+
 TEST_OK=true
+# shellcheck disable=SC2086
 if ! parallel \
+    ${jobs_arg} \
     ${progress} \
     --results "${SCENARIO_INFO_DIR}/{/.}/boot_and_run.log" \
     --joblog "${BOOT_TEST_JOB_LOG}" \
     --delay 5 \
-    bash -x ./bin/scenario.sh create-and-run ::: "${SCENARIOS_TO_RUN}"/*.sh ; then
+    bash -x ./bin/scenario.sh "${scenario_action}" ::: "${SCENARIOS_TO_RUN}"/*.sh ; then
    TEST_OK=false
 fi
 
diff --git a/test/bin/scenario.sh b/test/bin/scenario.sh
index 65ba2c026a..d6c8151ae8 100755
--- a/test/bin/scenario.sh
+++ b/test/bin/scenario.sh
@@ -1032,6 +1032,30 @@ remove_vm() {
     fi
 }
 
+# Power off all the VMs of the scenario without undefining them or
+# removing their storage. Frees the vCPUs and memory on the hypervisor
+# while keeping the domains and disks available for inspection.
+shutdown_scenario_vms() {
+    local vmdir
+    local vmname
+    local full_vmname
+    for vmdir in "${SCENARIO_INFO_DIR}/${SCENARIO}"/vms/*; do
+        if [ ! -d "${vmdir}" ]; then
+            continue
+        fi
+        vmname="$(basename "${vmdir}")"
+        full_vmname="$(full_vm_name "${vmname}")"
+        if sudo virsh dumpxml "${full_vmname}" >/dev/null; then
+            if ! sudo virsh dominfo "${full_vmname}" | grep '^State' | grep -q 'shut off'; then
+                sudo virsh destroy --graceful "${full_vmname}" || true
+            fi
+            if ! sudo virsh dominfo "${full_vmname}" | grep '^State' | grep -q 'shut off'; then
+                sudo virsh destroy "${full_vmname}" || true
+            fi
+        fi
+    done
+}
+
 # Configure the firewall in the VM based on the instructions in the documentation.
 configure_vm_firewall() {
     local -r vmname="$1"
@@ -1641,6 +1665,15 @@ case "${action}" in
         action_create "$@"
         action_run "$@"
         ;;
+    create-run-shutdown)
+        action_create "$@"
+        action_run "$@"
+        rc=0
+        sos_report true || rc=1
+        trap "close_junit" EXIT
+        shutdown_scenario_vms || echo "WARNING: failed to shut down the VMs for ${SCENARIO}"
+        exit "${rc}"
+        ;;
     *)
         error "Unknown instruction ${action}"
         usage
diff --git a/test/resources/oc.resource b/test/resources/oc.resource
index cba2eb13a8..24b90fb5d8 100644
--- a/test/resources/oc.resource
+++ b/test/resources/oc.resource
@@ -57,7 +57,7 @@ Oc Exec
     [Documentation]    Run 'oc exec' on a specific pod in the curret test namespace
     ...    Returns the command's combined STDOUT/STDER
     [Arguments]    ${pod}    ${cmd}    ${ns}=${NAMESPACE}    ${type}=pod
-    ${output}=    Run With Kubeconfig    oc exec -n ${ns} ${type}/${pod} -- /bin/bash -c '${cmd}'
+    ${output}=    Run With Kubeconfig    oc exec -n ${ns} ${type}/${pod} -- /bin/sh -c '${cmd}'
     RETURN    ${output}
 
 Oc Wait