fix(nvca): default NVMesh model cache volumes to nvcf-sc-30, not nvcf-sc

src/compute-plane-services/nvca/pkg/storage/cachebackend.go

@@ -78,6 +78,22 @@ func ModelCacheStorageClassName(override string) string {
 	return DefaultModelCacheStorageClassName
 }
 
+// nvmeshModelCacheStorageClassName resolves the storage class NVMesh model
+// cache volumes are provisioned on: the override when set, otherwise
+// NVMeshStorageClassName. NVCA only reaches the NVMesh reconciliation path
+// (doModelCacheNVMesh) once SelectHelmCacheBackend has already confirmed
+// NVMeshStorageClassName exists in the cluster, so defaulting to it here
+// keeps the volume's storage class aligned with the backend that was
+// actually selected, instead of falling back to the Samba-oriented
+// DefaultModelCacheStorageClassName.
+func nvmeshModelCacheStorageClassName(override string) string {
+	if override != "" {
+		return override
+	}
+
+	return NVMeshStorageClassName
+}
+
 // SelectHelmCacheBackend resolves the Helm model-cache storage backend. All
 // caching is gated on CachingSupport; the mechanism is then chosen by which
 // storage class the cluster provides, falling back to Samba (when

src/compute-plane-services/nvca/pkg/storage/cachebackend_test.go

@@ -172,6 +172,18 @@ func TestModelCacheStorageClassNameResolution(t *testing.T) {
 	assert.Equal(t, "custom-block-sc", ModelCacheStorageClassName("custom-block-sc"))
 }
 
+// TestNvmeshModelCacheStorageClassNameResolution pins the NVMesh path's
+// unconfigured default to NVMeshStorageClassName ("nvcf-sc-30"), not
+// DefaultModelCacheStorageClassName ("nvcf-sc"). Regression test for the bug
+// where doModelCacheNVMesh provisioned volumes on nvcf-sc even when
+// SelectHelmCacheBackend had already confirmed nvcf-sc-30 (NVMesh) was
+// available and selected the NVMesh backend.
+func TestNvmeshModelCacheStorageClassNameResolution(t *testing.T) {
+	assert.Equal(t, NVMeshStorageClassName, nvmeshModelCacheStorageClassName(""))
+	assert.Equal(t, "custom-nvmesh-sc", nvmeshModelCacheStorageClassName("custom-nvmesh-sc"))
+	assert.NotEqual(t, DefaultModelCacheStorageClassName, nvmeshModelCacheStorageClassName(""))
+}
+
 // TestSelectHelmCacheBackend_SambaClassLookupError proves a failed lookup of the
 // Samba backing class surfaces as an error rather than silently degrading to the
 // ephemeral cache: a transient API error must be retried, not treated as an

src/compute-plane-services/nvca/pkg/storage/modelcache.go

@@ -457,7 +457,7 @@ func (r *Reconciler) doModelCacheSamba(ctx context.Context,
 		func(ctx context.Context) error {
 			var e error
 			infraState, e = EnsureSambaModelCacheInfra(ctx, r.Client, cacheHandle,
-				r.cfg.Agent.SharedStorage.Server.Image, r.modelCacheStorageClass, smbResources, capacity)
+				r.cfg.Agent.SharedStorage.Server.Image, r.sambaModelCacheStorageClass, smbResources, capacity)
 			return e
 		},
 		oteltrace.WithAttributes(otelattr.String("nvcf.modelcache.handle", cacheHandle)),
@@ -488,7 +488,7 @@ func (r *Reconciler) doModelCacheSamba(ctx context.Context,
 			return reconcile.Result{}, r.terminalErrorWithMetricErr(modelcachetypes.ReasonSambaInfraTimeout,
 				fmt.Errorf("samba model cache server for handle %s still unavailable after %s, "+
 					"its backing PVC on storage class %s may be unbindable",
-					cacheHandle, waited.Round(time.Second), r.modelCacheStorageClass))
+					cacheHandle, waited.Round(time.Second), r.sambaModelCacheStorageClass))
 		}
 		log.V(1).Info("Samba model cache server not ready, requeuing", "waited", waited.Round(time.Second))
 		return reconcile.Result{RequeueAfter: defaultRequeueDelay}, nil

src/compute-plane-services/nvca/pkg/storage/modelcache_test.go

@@ -566,12 +566,17 @@ func TestGetPrimaryPV(t *testing.T) {
 }
 
 // newMountOptionDefaultsObjects builds the storage class and ConfigMap that the
-// reconciler consults to decide which mount option defaults apply.
+// reconciler consults to decide which mount option defaults apply. The
+// StorageClass is named NVMeshStorageClassName, not
+// DefaultModelCacheStorageClassName: newMountOptionsReconciler builds its
+// Reconciler with no storage class override, so it resolves the NVMesh
+// default (see TestModelCacheStorageClassResolvedOnce) and that is the class
+// name modelCacheProvisionerName looks up.
 func newMountOptionDefaultsObjects(provisioner string, cmData map[string]string) []client.Object {
 	objs := []client.Object{}
 	if provisioner != "" {
 		objs = append(objs, &storagev1.StorageClass{
-			ObjectMeta:  metav1.ObjectMeta{Name: DefaultModelCacheStorageClassName},
+			ObjectMeta:  metav1.ObjectMeta{Name: NVMeshStorageClassName},
 			Provisioner: provisioner,
 		})
 	}
@@ -746,9 +751,15 @@ func TestResolveCacheMountOptions_ConfigMapEditTakesEffect(t *testing.T) {
 
 // TestModelCacheStorageClassResolvedOnce covers the storage class NewReconciler
 // resolves for the life of the reconciler: the option override first (tests),
-// then the agent config value, then the default. The config value is the single
-// production source, read here and by model cache backend selection, so the
-// class that is checked cannot drift from the class volumes are created on.
+// then the agent config value, then the NVMesh default. The config value is
+// the single production source, read here and by model cache backend
+// selection, so the class that is checked cannot drift from the class volumes
+// are created on. This reconciler only provisions on the NVMesh path
+// (doModelCacheNVMesh), so the unconfigured default must be
+// NVMeshStorageClassName ("nvcf-sc-30"), not the Samba-oriented
+// DefaultModelCacheStorageClassName ("nvcf-sc") — see
+// TestNvmeshModelCacheStorageClassNameResolution for the regression this
+// guards against.
 func TestModelCacheStorageClassResolvedOnce(t *testing.T) {
 	tests := []struct {
 		name     string
@@ -757,8 +768,8 @@ func TestModelCacheStorageClassResolvedOnce(t *testing.T) {
 		want     string
 	}{
 		{
-			name: "unset falls back to the default",
-			want: DefaultModelCacheStorageClassName,
+			name: "unset falls back to the NVMesh default",
+			want: NVMeshStorageClassName,
 		},
 		{
 			name:     "option override wins",
@@ -788,6 +799,47 @@ func TestModelCacheStorageClassResolvedOnce(t *testing.T) {
 	}
 }
 
+// TestSambaModelCacheStorageClassResolvedOnce covers the Samba-side sibling of
+// modelCacheStorageClass: it must resolve to DefaultModelCacheStorageClassName
+// ("nvcf-sc") when unconfigured, independent of modelCacheStorageClass having
+// been changed to default to NVMeshStorageClassName ("nvcf-sc-30"). Regression
+// test: doModelCacheSamba (modelcache.go) must read
+// sambaModelCacheStorageClass, not modelCacheStorageClass, or the Samba
+// backend's backing PVC would try to land on the NVMesh class whenever no
+// explicit override is configured.
+func TestSambaModelCacheStorageClassResolvedOnce(t *testing.T) {
+	tests := []struct {
+		name     string
+		override string
+		agentCfg string
+		want     string
+	}{
+		{
+			name: "unset falls back to the Samba default",
+			want: DefaultModelCacheStorageClassName,
+		},
+		{
+			name:     "option override wins",
+			override: "custom-sc",
+			want:     "custom-sc",
+		},
+		{
+			name:     "agent config value is used when there is no override",
+			agentCfg: "cfg-sc",
+			want:     "cfg-sc",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := newModelCacheStorageClassReconciler(t, tt.agentCfg, tt.override)
+			assert.Equal(t, tt.want, r.sambaModelCacheStorageClass)
+			assert.NotEqual(t, NVMeshStorageClassName, r.sambaModelCacheStorageClass,
+				"Samba class must never silently resolve to the NVMesh class")
+		})
+	}
+}
+
 // newModelCacheStorageClassReconciler builds a Reconciler the way production
 // does, so the storage class resolution under test is the real one.
 func newModelCacheStorageClassReconciler(t *testing.T, agentCfg, override string) *Reconciler {
@@ -819,10 +871,10 @@ func TestApplyModelCacheStorageClass(t *testing.T) {
 		want       string
 	}{
 		{
-			name:       "spec value is replaced by the default",
+			name:       "spec value is replaced by the NVMesh default",
 			configured: "",
 			specSC:     ptr("some-other-sc"),
-			want:       DefaultModelCacheStorageClassName,
+			want:       NVMeshStorageClassName,
 		},
 		{
 			name:       "spec value is replaced by the configured override",
@@ -1572,6 +1624,20 @@ func TestReconcile_ModelCacheSamba(t *testing.T) {
 	}
 	require.NoError(t, c.Get(ctx, client.ObjectKey{Name: "samba-rw-pv-" + cacheHandle}, &corev1.PersistentVolume{}))
 
+	// The Samba server's own backing data PVC must stay on the Samba-oriented
+	// default (nvcf-sc), not the NVMesh default (nvcf-sc-30), even though this
+	// reconciler is built with no explicit override (nvcaCfg above). Regression
+	// test: doModelCacheSamba used to read the NVMesh-resolved
+	// r.modelCacheStorageClass for this PVC too, which would have pointed the
+	// Samba backing storage at nvcf-sc-30 whenever it was unconfigured.
+	dataPVC := &corev1.PersistentVolumeClaim{}
+	require.NoError(t, c.Get(ctx,
+		client.ObjectKey{Name: SambaModelCacheBackingPVCName(cacheHandle), Namespace: ModelCacheInitNamespace}, dataPVC))
+	if assert.NotNil(t, dataPVC.Spec.StorageClassName) {
+		assert.Equal(t, DefaultModelCacheStorageClassName, *dataPVC.Spec.StorageClassName,
+			"Samba backing data PVC must default to nvcf-sc, not the NVMesh class")
+	}
+
 	// Drive the writer pod to running so the request moves to InitRunning.
 	initJobPod := &corev1.Pod{}
 	initJobPod.Name, initJobPod.Namespace = initJob.Spec.Template.Name+"-foobar", initJob.Namespace

src/compute-plane-services/nvca/pkg/storage/reconcile.go

@@ -201,7 +201,19 @@ func NewReconciler(
 
 	// Resolve the model cache storage class once: it cannot change for the life
 	// of the reconciler, so every later use reads the field directly.
-	reconciler.modelCacheStorageClass = ModelCacheStorageClassName(reconciler.modelCacheStorageClass)
+	// modelCacheStorageClassOverride is the same unresolved value (option, then
+	// Agent.ModelCache) used to resolve both the NVMesh and Samba class names
+	// below, and the value model cache backend selection checks against
+	// independently. It is deliberately resolved twice, with different
+	// defaults, because doModelCacheNVMesh and doModelCacheSamba are only ever
+	// reached for their respective backend and need different unconfigured
+	// defaults (NVMeshStorageClassName vs. the Samba-oriented
+	// DefaultModelCacheStorageClassName) — a single shared resolved value would
+	// hand doModelCacheSamba the NVMesh class (or vice versa) whenever the
+	// operator has not set an explicit override.
+	modelCacheStorageClassOverride := reconciler.modelCacheStorageClass
+	reconciler.modelCacheStorageClass = nvmeshModelCacheStorageClassName(modelCacheStorageClassOverride)
+	reconciler.sambaModelCacheStorageClass = ModelCacheStorageClassName(modelCacheStorageClassOverride)
 
 	return reconciler
 }
@@ -220,20 +232,26 @@ type Reconciler struct {
 	k8sTimeConfig         *k8sutil.TimeConfig
 	csiVolumeMountOptions []string
 
-	// modelCacheStorageClass is the storage class model cache volumes are
-	// provisioned on and whose provisioner selects the mount option defaults.
-	// NewReconciler resolves it once (option, then Agent.ModelCache, then the
-	// default), so it is always a concrete class name. NVCA owns this choice
-	// rather than taking it from the request spec, so every model cache volume
-	// in a cluster lands on the same class; model cache backend selection reads
-	// the same config value before choosing a backend that needs the class.
+	// modelCacheStorageClass is the storage class NVMesh model cache volumes
+	// are provisioned on and whose provisioner selects the mount option
+	// defaults. NewReconciler resolves it once (option, then Agent.ModelCache,
+	// then NVMeshStorageClassName), so it is always a concrete class name.
+	// NVCA owns this choice rather than taking it from the request spec, so
+	// every NVMesh model cache volume in a cluster lands on the same class.
+	// sambaModelCacheStorageClass is the analogous resolved class for the
+	// Samba backend's own backing PVC (doModelCacheSamba), resolved from the
+	// same unconfigured override but defaulting to
+	// DefaultModelCacheStorageClassName instead — see NewReconciler. Model
+	// cache backend selection reads the unresolved config value independently,
+	// before choosing a backend that needs one of these classes.
 	// cacheMountOptionsConfigMap holds the mount option defaults per
 	// provisioner. modelCacheProvisioner is the one time init: a StorageClass
 	// provisioner is immutable, so it is read once and kept. The ConfigMap is
 	// read on each use so operator edits take effect.
-	modelCacheStorageClass     string
-	cacheMountOptionsConfigMap string
-	modelCacheProvisioner      atomic.Pointer[string]
+	modelCacheStorageClass      string
+	sambaModelCacheStorageClass string
+	cacheMountOptionsConfigMap  string
+	modelCacheProvisioner       atomic.Pointer[string]
 
 	tracer            oteltrace.Tracer
 	nowFunc           func() time.Time