diff --git a/mock/service/controller.go b/mock/service/controller.go
index 545b2514..e2d802d7 100644
--- a/mock/service/controller.go
+++ b/mock/service/controller.go
@@ -32,6 +32,12 @@ func (s *service) CreateVolume(
 
 	// Check to see if the volume already exists.
 	if i, v := s.findVolByName(ctx, req.Name); i >= 0 {
+		// Requested volume name already exists, need to check if the existing volume's
+		// capacity is more or equal to new request's capacity.
+		if v.GetCapacityBytes() < req.GetCapacityRange().GetRequiredBytes() {
+			return nil, status.Error(codes.AlreadyExists,
+				fmt.Sprintf("Volume with name %s already exists", req.GetName()))
+		}
 		return &csi.CreateVolumeResponse{Volume: &v}, nil
 	}
 
@@ -280,7 +286,7 @@ func (s *service) GetCapacity(
 	*csi.GetCapacityResponse, error) {
 
 	return &csi.GetCapacityResponse{
-		AvailableCapacity: tib100,
+		AvailableCapacity: MaxStorageCapacity,
 	}, nil
 }
 
diff --git a/pkg/sanity/controller.go b/pkg/sanity/controller.go
index 7a0fb964..e6c6ad9b 100644
--- a/pkg/sanity/controller.go
+++ b/pkg/sanity/controller.go
@@ -216,7 +216,6 @@ var _ = Describe("CreateVolume [Controller Server]", func() {
 		Expect(err).NotTo(HaveOccurred())
 	})
 
-	// Pending fix in mock file
 	It("should return appropriate values SingleNodeWriter WithCapacity 1Gi Type:Mount", func() {
 
 		By("creating a volume")
@@ -240,12 +239,20 @@ var _ = Describe("CreateVolume [Controller Server]", func() {
 					RequiredBytes: size,
 				},
 			})
-		Expect(err).NotTo(HaveOccurred())
-		Expect(vol).NotTo(BeNil())
-		Expect(vol.GetVolume()).NotTo(BeNil())
-		Expect(vol.GetVolume().GetId()).NotTo(BeEmpty())
-		Expect(vol.GetVolume().GetCapacityBytes()).To(Equal(size))
+		if serverError, ok := status.FromError(err); ok {
+			if serverError.Code() == codes.OutOfRange || serverError.Code() == codes.Unimplemented {
+				Skip("Required bytes not supported")
+			} else {
+				Expect(err).NotTo(HaveOccurred())
+			}
+		} else {
 
+			Expect(err).NotTo(HaveOccurred())
+			Expect(vol).NotTo(BeNil())
+			Expect(vol.GetVolume()).NotTo(BeNil())
+			Expect(vol.GetVolume().GetId()).NotTo(BeEmpty())
+			Expect(vol.GetVolume().GetCapacityBytes()).To(Equal(size))
+		}
 		By("cleaning up deleting the volume")
 		_, err = c.DeleteVolume(
 			context.Background(),
@@ -254,6 +261,154 @@ var _ = Describe("CreateVolume [Controller Server]", func() {
 			})
 		Expect(err).NotTo(HaveOccurred())
 	})
+	It("should not fail when requesting to create a volume with already exisiting name and same capacity.", func() {
+
+		By("creating a volume")
+		name := "sanity"
+		size := int64(1 * 1024 * 1024 * 1024)
+		vol1, err := c.CreateVolume(
+			context.Background(),
+			&csi.CreateVolumeRequest{
+				Name: name,
+				VolumeCapabilities: []*csi.VolumeCapability{
+					{
+						AccessType: &csi.VolumeCapability_Mount{
+							Mount: &csi.VolumeCapability_MountVolume{},
+						},
+						AccessMode: &csi.VolumeCapability_AccessMode{
+							Mode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
+						},
+					},
+				},
+				CapacityRange: &csi.CapacityRange{
+					RequiredBytes: size,
+				},
+			})
+		Expect(err).NotTo(HaveOccurred())
+		Expect(vol1).NotTo(BeNil())
+		Expect(vol1.GetVolume()).NotTo(BeNil())
+		Expect(vol1.GetVolume().GetId()).NotTo(BeEmpty())
+		Expect(vol1.GetVolume().GetCapacityBytes()).To(Equal(size))
+		vol2, err := c.CreateVolume(
+			context.Background(),
+			&csi.CreateVolumeRequest{
+				Name: name,
+				VolumeCapabilities: []*csi.VolumeCapability{
+					{
+						AccessType: &csi.VolumeCapability_Mount{
+							Mount: &csi.VolumeCapability_MountVolume{},
+						},
+						AccessMode: &csi.VolumeCapability_AccessMode{
+							Mode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
+						},
+					},
+				},
+				CapacityRange: &csi.CapacityRange{
+					RequiredBytes: size,
+				},
+			})
+		Expect(err).NotTo(HaveOccurred())
+		Expect(vol2).NotTo(BeNil())
+		Expect(vol2.GetVolume()).NotTo(BeNil())
+		Expect(vol2.GetVolume().GetId()).NotTo(BeEmpty())
+		Expect(vol2.GetVolume().GetCapacityBytes()).To(Equal(size))
+		Expect(vol1.GetVolume().GetId()).To(Equal(vol2.GetVolume().GetId()))
+
+		By("cleaning up deleting the volume")
+		_, err = c.DeleteVolume(
+			context.Background(),
+			&csi.DeleteVolumeRequest{
+				VolumeId: vol1.GetVolume().GetId(),
+			})
+		Expect(err).NotTo(HaveOccurred())
+	})
+	It("should fail when requesting to create a volume with already exisiting name and different capacity.", func() {
+
+		By("creating a volume")
+		name := "sanity"
+		size1 := int64(1 * 1024 * 1024 * 1024)
+		vol1, err := c.CreateVolume(
+			context.Background(),
+			&csi.CreateVolumeRequest{
+				Name: name,
+				VolumeCapabilities: []*csi.VolumeCapability{
+					{
+						AccessType: &csi.VolumeCapability_Mount{
+							Mount: &csi.VolumeCapability_MountVolume{},
+						},
+						AccessMode: &csi.VolumeCapability_AccessMode{
+							Mode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
+						},
+					},
+				},
+				CapacityRange: &csi.CapacityRange{
+					RequiredBytes: size1,
+				},
+			})
+		Expect(err).ToNot(HaveOccurred())
+		Expect(vol1).NotTo(BeNil())
+		Expect(vol1.GetVolume()).NotTo(BeNil())
+		Expect(vol1.GetVolume().GetId()).NotTo(BeEmpty())
+		size2 := int64(2 * 1024 * 1024 * 1024)
+		_, err = c.CreateVolume(
+			context.Background(),
+			&csi.CreateVolumeRequest{
+				Name: name,
+				VolumeCapabilities: []*csi.VolumeCapability{
+					{
+						AccessType: &csi.VolumeCapability_Mount{
+							Mount: &csi.VolumeCapability_MountVolume{},
+						},
+						AccessMode: &csi.VolumeCapability_AccessMode{
+							Mode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
+						},
+					},
+				},
+				CapacityRange: &csi.CapacityRange{
+					RequiredBytes: size2,
+				},
+			})
+		Expect(err).To(HaveOccurred())
+		serverError, ok := status.FromError(err)
+		Expect(ok).To(BeTrue())
+		Expect(serverError.Code()).To(Equal(codes.AlreadyExists))
+
+		By("cleaning up deleting the volume")
+		_, err = c.DeleteVolume(
+			context.Background(),
+			&csi.DeleteVolumeRequest{
+				VolumeId: vol1.GetVolume().GetId(),
+			})
+		Expect(err).NotTo(HaveOccurred())
+	})
+	It("should fail when requesting to create a volume exceeding Maximum Capacity", func() {
+
+		By("creating a volume")
+		name := "sanity"
+		size := int64(10 * 1024 * 1024 * 1024 * 1024)
+		_, err := c.CreateVolume(
+			context.Background(),
+			&csi.CreateVolumeRequest{
+				Name: name,
+				VolumeCapabilities: []*csi.VolumeCapability{
+					{
+						AccessType: &csi.VolumeCapability_Mount{
+							Mount: &csi.VolumeCapability_MountVolume{},
+						},
+						AccessMode: &csi.VolumeCapability_AccessMode{
+							Mode: csi.VolumeCapability_AccessMode_SINGLE_NODE_WRITER,
+						},
+					},
+				},
+				CapacityRange: &csi.CapacityRange{
+					RequiredBytes: size,
+				},
+			})
+		Expect(err).To(HaveOccurred())
+		serverError, ok := status.FromError(err)
+		Expect(ok).To(BeTrue())
+		Expect(serverError.Code()).To(Equal(codes.OutOfRange))
+	})
 })
 
 var _ = Describe("DeleteVolume [Controller Server]", func() {