diff --git a/manifests/backend/dellemc_powermax.pp b/manifests/backend/dellemc_powermax.pp
index d1c7bb21..603c45ec 100644
--- a/manifests/backend/dellemc_powermax.pp
+++ b/manifests/backend/dellemc_powermax.pp
@@ -59,24 +59,19 @@ define cinder::backend::dellemc_powermax (
   $powermax_array,
   $powermax_srp,
   $powermax_port_groups,
-  $powermax_storage_protocol     = 'iSCSI',
-  $volume_backend_name           = $name,
-  $backend_availability_zone     = $facts['os_service_default'],
-  Hash $extra_options            = {},
-  Boolean $manage_volume_type    = false,
+  Enum['iSCSI', 'FC'] $powermax_storage_protocol = 'iSCSI',
+  $volume_backend_name                           = $name,
+  $backend_availability_zone                     = $facts['os_service_default'],
+  Hash $extra_options                            = {},
+  Boolean $manage_volume_type                    = false,
 ) {
 
   include cinder::deps
   include cinder::params
 
-  if $powermax_storage_protocol == 'iSCSI' {
-    $volume_driver = 'cinder.volume.drivers.dell_emc.powermax.iscsi.PowerMaxISCSIDriver'
-  }
-  elsif $powermax_storage_protocol == 'FC' {
-    $volume_driver = 'cinder.volume.drivers.dell_emc.powermax.fc.PowerMaxFCDriver'
-  }
-  else {
-    fail('The cinder::backend::dellemc_powermax powermax_storage_protocol specified is not valid. It should be iSCSI or FC')
+  $volume_driver = $powermax_storage_protocol ? {
+    'FC'    => 'cinder.volume.drivers.dell_emc.powermax.fc.PowerMaxFCDriver',
+    default => 'cinder.volume.drivers.dell_emc.powermax.iscsi.PowerMaxISCSIDriver',
   }
 
   $_powermax_port_groups = join(any2array($powermax_port_groups), ',')
diff --git a/manifests/backend/dellemc_powerstore.pp b/manifests/backend/dellemc_powerstore.pp
index 8092a69d..123045e8 100644
--- a/manifests/backend/dellemc_powerstore.pp
+++ b/manifests/backend/dellemc_powerstore.pp
@@ -46,25 +46,17 @@ define cinder::backend::dellemc_powerstore (
   $san_ip,
   $san_login,
   $san_password,
-  $powerstore_ports            = $facts['os_service_default'],
-  $storage_protocol            = 'iSCSI',
-  $volume_backend_name         = $name,
-  $backend_availability_zone   = $facts['os_service_default'],
-  Boolean $manage_volume_type  = false,
-  Hash $extra_options          = {},
+  $powerstore_ports                     = $facts['os_service_default'],
+  Enum['iSCSI', 'FC'] $storage_protocol = 'iSCSI',
+  $volume_backend_name                  = $name,
+  $backend_availability_zone            = $facts['os_service_default'],
+  Boolean $manage_volume_type           = false,
+  Hash $extra_options                   = {},
 ) {
 
   include cinder::deps
 
-  if $storage_protocol == 'iSCSI' {
-    $driver = 'dell_emc.powerstore.driver.PowerStoreDriver'
-  }
-  elsif $storage_protocol == 'FC' {
-    $driver = 'dell_emc.powerstore.driver.PowerStoreDriver'
-  }
-  else {
-    fail('The cinder::backend::dellemc_powerstore storage_protocol specified is not valid. It should be iSCSI or FC')
-  }
+  $driver = 'dell_emc.powerstore.driver.PowerStoreDriver'
 
   cinder_config {
     "${name}/volume_backend_name":       value => $volume_backend_name;
diff --git a/manifests/backend/dellemc_sc.pp b/manifests/backend/dellemc_sc.pp
index c1fda684..0f6c96e9 100644
--- a/manifests/backend/dellemc_sc.pp
+++ b/manifests/backend/dellemc_sc.pp
@@ -98,35 +98,30 @@ define cinder::backend::dellemc_sc (
   $san_login,
   $san_password,
   $dell_sc_ssn,
-  $target_ip_address            = undef,
-  $volume_backend_name          = $name,
-  $backend_availability_zone    = $facts['os_service_default'],
-  $dell_sc_api_port             = $facts['os_service_default'],
-  $dell_sc_server_folder        = 'srv',
-  $dell_sc_verify_cert          = $facts['os_service_default'],
-  $dell_sc_volume_folder        = 'vol',
-  $target_port                  = $facts['os_service_default'],
-  $excluded_domain_ips          = $facts['os_service_default'],
-  $secondary_san_ip             = $facts['os_service_default'],
-  $secondary_san_login          = $facts['os_service_default'],
-  $secondary_san_password       = $facts['os_service_default'],
-  $secondary_sc_api_port        = $facts['os_service_default'],
-  Boolean $manage_volume_type   = false,
-  $use_multipath_for_image_xfer = true,
-  $sc_storage_protocol          = 'iSCSI',
-  Hash $extra_options           = {},
+  $target_ip_address                       = undef,
+  $volume_backend_name                     = $name,
+  $backend_availability_zone               = $facts['os_service_default'],
+  $dell_sc_api_port                        = $facts['os_service_default'],
+  $dell_sc_server_folder                   = 'srv',
+  $dell_sc_verify_cert                     = $facts['os_service_default'],
+  $dell_sc_volume_folder                   = 'vol',
+  $target_port                             = $facts['os_service_default'],
+  $excluded_domain_ips                     = $facts['os_service_default'],
+  $secondary_san_ip                        = $facts['os_service_default'],
+  $secondary_san_login                     = $facts['os_service_default'],
+  $secondary_san_password                  = $facts['os_service_default'],
+  $secondary_sc_api_port                   = $facts['os_service_default'],
+  Boolean $manage_volume_type              = false,
+  $use_multipath_for_image_xfer            = true,
+  Enum['iSCSI', 'FC'] $sc_storage_protocol = 'iSCSI',
+  Hash $extra_options                      = {},
 ) {
 
   include cinder::deps
 
-  if $sc_storage_protocol == 'iSCSI' {
-    $volume_driver = 'cinder.volume.drivers.dell_emc.sc.storagecenter_iscsi.SCISCSIDriver'
-  }
-  elsif $sc_storage_protocol == 'FC' {
-    $volume_driver = 'cinder.volume.drivers.dell_emc.sc.storagecenter_fc.SCFCDriver'
-  }
-  else {
-    fail('The cinder::backend::dellemc_sc sc_storage_protocol specified is not valid. It should be iSCSI or FC')
+  $volume_driver = $sc_storage_protocol ? {
+    'FC'    => 'cinder.volume.drivers.dell_emc.sc.storagecenter_fc.SCFCDriver',
+    default => 'cinder.volume.drivers.dell_emc.sc.storagecenter_iscsi.SCISCSIDriver',
   }
 
   cinder_config {
diff --git a/manifests/backend/dellemc_xtremio.pp b/manifests/backend/dellemc_xtremio.pp
index d14f8a20..f7f23ab2 100644
--- a/manifests/backend/dellemc_xtremio.pp
+++ b/manifests/backend/dellemc_xtremio.pp
@@ -67,27 +67,22 @@ define cinder::backend::dellemc_xtremio (
   $san_login,
   $san_password,
   $xtremio_cluster_name,
-  $volume_backend_name               = $name,
-  $backend_availability_zone         = $facts['os_service_default'],
-  $xtremio_array_busy_retry_count    = $facts['os_service_default'],
-  $xtremio_array_busy_retry_interval = $facts['os_service_default'],
-  $xtremio_volumes_per_glance_cache  = $facts['os_service_default'],
-  Boolean $manage_volume_type        = false,
-  $xtremio_storage_protocol          = 'iSCSI',
-  $xtremio_ports                     = $facts['os_service_default'],
-  Hash $extra_options                = {},
+  $volume_backend_name                          = $name,
+  $backend_availability_zone                    = $facts['os_service_default'],
+  $xtremio_array_busy_retry_count               = $facts['os_service_default'],
+  $xtremio_array_busy_retry_interval            = $facts['os_service_default'],
+  $xtremio_volumes_per_glance_cache             = $facts['os_service_default'],
+  Boolean $manage_volume_type                   = false,
+  Enum['iSCSI', 'FC'] $xtremio_storage_protocol = 'iSCSI',
+  $xtremio_ports                                = $facts['os_service_default'],
+  Hash $extra_options                           = {},
 ) {
 
   include cinder::deps
 
-  if $xtremio_storage_protocol == 'iSCSI' {
-    $driver = 'dell_emc.xtremio.XtremIOISCSIDriver'
-  }
-  elsif $xtremio_storage_protocol == 'FC' {
-    $driver = 'dell_emc.xtremio.XtremIOFCDriver'
-  }
-  else {
-    fail('The cinder::backend::dellemc_xtremio xtremio_storage_protocol specified is not valid. It should be iSCSI or FC')
+  $driver = $xtremio_storage_protocol ? {
+    'FC'    => 'dell_emc.xtremio.XtremIOFCDriver',
+    default => 'dell_emc.xtremio.XtremIOISCSIDriver',
   }
 
   cinder_config {
diff --git a/manifests/backend/ibm_svf.pp b/manifests/backend/ibm_svf.pp
index f1bf810f..d6e1c05f 100644
--- a/manifests/backend/ibm_svf.pp
+++ b/manifests/backend/ibm_svf.pp
@@ -70,29 +70,24 @@ define cinder::backend::ibm_svf (
   $san_login,
   $san_password,
   $storwize_svc_volpool_name,
-  $storwize_svc_allow_tenant_qos     = $facts['os_service_default'],
-  $storwize_svc_connection_protocol  = 'iSCSI',
-  $storwize_svc_iscsi_chap_enabled   = $facts['os_service_default'],
-  $storwize_svc_retain_aux_volume    = $facts['os_service_default'],
-  $storwize_portset                  = $facts['os_service_default'],
-  $volume_backend_name               = $name,
-  $backend_availability_zone         = $facts['os_service_default'],
-  Hash $extra_options                = {},
-  Boolean $manage_volume_type        = false,
+  $storwize_svc_allow_tenant_qos                        = $facts['os_service_default'],
+  Enum['iSCSI', 'FC'] $storwize_svc_connection_protocol = 'iSCSI',
+  $storwize_svc_iscsi_chap_enabled                      = $facts['os_service_default'],
+  $storwize_svc_retain_aux_volume                       = $facts['os_service_default'],
+  $storwize_portset                                     = $facts['os_service_default'],
+  $volume_backend_name                                  = $name,
+  $backend_availability_zone                            = $facts['os_service_default'],
+  Hash $extra_options                                   = {},
+  Boolean $manage_volume_type                           = false,
 ) {
 
   include cinder::deps
 
   # NOTE: Svf was earlier called as storwize/svc driver, so the cinder
   # configuration parameters were named accordingly.
-  if $storwize_svc_connection_protocol == 'iSCSI' {
-    $volume_driver = 'cinder.volume.drivers.ibm.storwize_svc.storwize_svc_iscsi.StorwizeSVCISCSIDriver'
-  }
-  elsif $storwize_svc_connection_protocol == 'FC' {
-    $volume_driver = 'cinder.volume.drivers.ibm.storwize_svc.storwize_svc_fc.StorwizeSVCFCDriver'
-  }
-  else {
-    fail('The cinder::backend::ibm_svf storwize_svc_connection_protocol specified is not valid. It should be iSCSI or FC')
+  $volume_driver = $storwize_svc_connection_protocol ? {
+    'FC'    => 'cinder.volume.drivers.ibm.storwize_svc.storwize_svc_fc.StorwizeSVCFCDriver',
+    default => 'cinder.volume.drivers.ibm.storwize_svc.storwize_svc_iscsi.StorwizeSVCISCSIDriver',
   }
 
   cinder_config {
diff --git a/manifests/backend/pure.pp b/manifests/backend/pure.pp
index 9b892105..10a9a3b8 100644
--- a/manifests/backend/pure.pp
+++ b/manifests/backend/pure.pp
@@ -95,34 +95,29 @@
 define cinder::backend::pure(
   $san_ip,
   $pure_api_token,
-  $volume_backend_name          = $name,
-  $backend_availability_zone    = $facts['os_service_default'],
-  $pure_storage_protocol        = 'iSCSI',
-  $use_chap_auth                = false,
-  $use_multipath_for_image_xfer = true,
-  Boolean $manage_volume_type   = false,
-  $image_volume_cache_enabled   = true,
-  $pure_host_personality        = $facts['os_service_default'],
-  $pure_eradicate_on_delete     = $facts['os_service_default'],
-  $pure_nvme_transport          = $facts['os_service_default'],
-  $pure_nvme_cidr               = $facts['os_service_default'],
-  $pure_nvme_cidr_list          = $facts['os_service_default'],
-  $pure_iscsi_cidr              = $facts['os_service_default'],
-  $pure_iscsi_cidr_list         = $facts['os_service_default'],
-  Hash $extra_options           = {},
+  $volume_backend_name                               = $name,
+  $backend_availability_zone                         = $facts['os_service_default'],
+  Enum['iSCSI', 'FC', 'NVMe'] $pure_storage_protocol = 'iSCSI',
+  $use_chap_auth                                     = false,
+  $use_multipath_for_image_xfer                      = true,
+  Boolean $manage_volume_type                        = false,
+  $image_volume_cache_enabled                        = true,
+  $pure_host_personality                             = $facts['os_service_default'],
+  $pure_eradicate_on_delete                          = $facts['os_service_default'],
+  $pure_nvme_transport                               = $facts['os_service_default'],
+  $pure_nvme_cidr                                    = $facts['os_service_default'],
+  $pure_nvme_cidr_list                               = $facts['os_service_default'],
+  $pure_iscsi_cidr                                   = $facts['os_service_default'],
+  $pure_iscsi_cidr_list                              = $facts['os_service_default'],
+  Hash $extra_options                                = {},
 ) {
 
   include cinder::deps
 
   $volume_driver = $pure_storage_protocol ? {
     'FC'    => 'cinder.volume.drivers.pure.PureFCDriver',
-    'iSCSI' => 'cinder.volume.drivers.pure.PureISCSIDriver',
     'NVMe'  => 'cinder.volume.drivers.pure.PureNVMEDriver',
-    default => undef,
-  }
-
-  if ! $volume_driver {
-    fail('Invalid pure_storage_protocol. It should be FC, iSCSI or NVMe')
+    default => 'cinder.volume.drivers.pure.PureISCSIDriver',
   }
 
   cinder_config {
diff --git a/spec/defines/cinder_backend_dellemc_powermax_spec.rb b/spec/defines/cinder_backend_dellemc_powermax_spec.rb
index b022ab9a..63154b99 100644
--- a/spec/defines/cinder_backend_dellemc_powermax_spec.rb
+++ b/spec/defines/cinder_backend_dellemc_powermax_spec.rb
@@ -75,9 +75,7 @@ describe 'cinder::backend::dellemc_powermax' do
       end
 
       it 'should raise an error' do
-        is_expected.to compile.and_raise_error(
-          /The cinder::backend::dellemc_powermax powermax_storage_protocol specified is not valid. It should be iSCSI or FC/
-        )
+        is_expected.to compile.and_raise_error(/Evaluation Error/)
       end
     end
 
diff --git a/spec/defines/cinder_backend_dellemc_powerstore_spec.rb b/spec/defines/cinder_backend_dellemc_powerstore_spec.rb
index a205459f..ed3b729b 100644
--- a/spec/defines/cinder_backend_dellemc_powerstore_spec.rb
+++ b/spec/defines/cinder_backend_dellemc_powerstore_spec.rb
@@ -66,9 +66,7 @@ describe 'cinder::backend::dellemc_powerstore' do
       end
 
       it 'should raise an error' do
-        is_expected.to compile.and_raise_error(
-          /The cinder::backend::dellemc_powerstore storage_protocol specified is not valid. It should be iSCSI or FC/
-        )
+        is_expected.to compile.and_raise_error(/Evaluation Error/)
       end
     end
   end
diff --git a/spec/defines/cinder_backend_dellemc_sc_spec.rb b/spec/defines/cinder_backend_dellemc_sc_spec.rb
index 5ce5b75d..32723ccb 100644
--- a/spec/defines/cinder_backend_dellemc_sc_spec.rb
+++ b/spec/defines/cinder_backend_dellemc_sc_spec.rb
@@ -84,9 +84,7 @@ describe 'cinder::backend::dellemc_sc' do
       end
 
       it 'should raise an error' do
-        is_expected.to compile.and_raise_error(
-          /The cinder::backend::dellemc_sc sc_storage_protocol specified is not valid. It should be iSCSI or FC/
-        )
+        is_expected.to compile.and_raise_error(/Evaluation Error/)
       end
     end
 
diff --git a/spec/defines/cinder_backend_dellemc_xtremio_spec.rb b/spec/defines/cinder_backend_dellemc_xtremio_spec.rb
index 921e1bf9..745fa2e1 100644
--- a/spec/defines/cinder_backend_dellemc_xtremio_spec.rb
+++ b/spec/defines/cinder_backend_dellemc_xtremio_spec.rb
@@ -69,9 +69,7 @@ describe 'cinder::backend::dellemc_xtremio' do
       end
 
       it 'should raise an error' do
-        is_expected.to compile.and_raise_error(
-          /The cinder::backend::dellemc_xtremio xtremio_storage_protocol specified is not valid. It should be iSCSI or FC/
-        )
+        is_expected.to compile.and_raise_error(/Evaluation Error/)
       end
     end
 
diff --git a/spec/defines/cinder_backend_ibm_svf_spec.rb b/spec/defines/cinder_backend_ibm_svf_spec.rb
index 03ed7dd8..7701537b 100644
--- a/spec/defines/cinder_backend_ibm_svf_spec.rb
+++ b/spec/defines/cinder_backend_ibm_svf_spec.rb
@@ -51,9 +51,7 @@ describe 'cinder::backend::ibm_svf' do
       end
 
       it 'should raise an error' do
-        is_expected.to compile.and_raise_error(
-          /The cinder::backend::ibm_svf storwize_svc_connection_protocol specified is not valid. It should be iSCSI or FC/
-        )
+        is_expected.to compile.and_raise_error(/Evaluation Error/)
       end
     end