Data cache support for K8s 1.31

Dockerfile

@@ -27,7 +27,7 @@ FROM gke.gcr.io/debian-base:bookworm-v1.0.4-gke.2 as debian
 
 # Install necessary dependencies
 # google_nvme_id script depends on the following packages: nvme-cli, xxd, bash
-RUN clean-install util-linux e2fsprogs mount ca-certificates udev xfsprogs nvme-cli xxd bash
+RUN clean-install util-linux e2fsprogs mount ca-certificates udev xfsprogs nvme-cli xxd bash kmod lvm2 mdadm
 
 # Since we're leveraging apt to pull in dependencies, we use `gcr.io/distroless/base` because it includes glibc.
 FROM gcr.io/distroless/base-debian12 as distroless-base
@@ -56,6 +56,35 @@ COPY --from=debian /sbin/e2fsck /sbin/e2fsck
 COPY --from=debian /sbin/fsck /sbin/fsck
 COPY --from=debian /sbin/fsck* /sbin/
 COPY --from=debian /sbin/fsck.xfs /sbin/fsck.xfs
+# Add dependencies for LVM
+COPY --from=debian /etc/lvm /lvm-tmp/lvm
+COPY --from=debian /lib/systemd/system/blk-availability.service /lib/systemd/system/blk-availability.service
+COPY --from=debian /lib/systemd/system/lvm2-lvmpolld.service /lib/systemd/system/lvm2-lvmpolld.service
+COPY --from=debian /lib/systemd/system/lvm2-lvmpolld.socket /lib/systemd/system/lvm2-lvmpolld.socket
+COPY --from=debian /lib/systemd/system/lvm2-monitor.service /lib/systemd/system/lvm2-monitor.service
+COPY --from=debian /lib/udev/rules.d/56-lvm.rules /lib/udev/rules.d/56-lvm.rules
+COPY --from=debian /sbin/fsadm /sbin/fsadm
+COPY --from=debian /sbin/lvm /sbin/lvm
+COPY --from=debian /sbin/lvmdump /sbin/lvmdump
+COPY --from=debian /sbin/lvmpolld /sbin/lvmpolld
+COPY --from=debian /usr/lib/tmpfiles.d /usr/lib/tmpfiles.d
+COPY --from=debian /usr/lib/tmpfiles.d/lvm2.conf /usr/lib/tmpfiles.d/lvm2.conf
+COPY --from=debian /sbin/lv* /sbin/
+COPY --from=debian /sbin/pv* /sbin/
+COPY --from=debian /sbin/vg* /sbin/
+COPY --from=debian /bin/lsblk /bin/lsblk
+COPY --from=debian /sbin/modprobe /sbin/modprobe
+COPY --from=debian /lib/udev /lib/udev
+COPY --from=debian /lib/udev/rules.d /lib/udev/rules.d
+COPY --from=debian /lib/udev/rules.d/55-dm.rules /lib/udev/rules.d/55-dm.rules
+COPY --from=debian /lib/udev/rules.d/60-persistent-storage-dm.rules /lib/udev/rules.d/60-persistent-storage-dm.rules
+COPY --from=debian /lib/udev/rules.d/95-dm-notify.rules /lib/udev/rules.d/95-dm-notify.rules
+COPY --from=debian /sbin/blkdeactivate /sbin/blkdeactivate
+COPY --from=debian /sbin/dmsetup /sbin/dmsetup
+COPY --from=debian /sbin/dmstats /sbin/dmstats
+COPY --from=debian /bin/ls /bin/ls
+# End of dependencies for LVM
+COPY --from=debian /sbin/mdadm /sbin/mdadm
 COPY --from=debian /sbin/mke2fs /sbin/mke2fs
 COPY --from=debian /sbin/mkfs* /sbin/
 COPY --from=debian /sbin/resize2fs /sbin/resize2fs
@@ -71,14 +100,20 @@ COPY --from=debian /bin/date /bin/date
 COPY --from=debian /bin/grep /bin/grep
 COPY --from=debian /bin/sed /bin/sed
 COPY --from=debian /bin/ln /bin/ln
+COPY --from=debian /bin/cp /bin/cp
 COPY --from=debian /bin/udevadm /bin/udevadm
 
 # Copy shared libraries into distroless base.
 COPY --from=debian /lib/${LIB_DIR_PREFIX}-linux-gnu/libselinux.so.1 \
+                   /lib/${LIB_DIR_PREFIX}-linux-gnu/libdl.so.2 \
+                   /lib/${LIB_DIR_PREFIX}-linux-gnu/libpthread.so.0 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libtinfo.so.6 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libe2p.so.2 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libcom_err.so.2 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libdevmapper.so.1.02.1 \
+                   /lib/${LIB_DIR_PREFIX}-linux-gnu/libm.so.6 \
+                   /lib/${LIB_DIR_PREFIX}-linux-gnu/libc.so.6 \
+                   /lib/${LIB_DIR_PREFIX}-linux-gnu/libdevmapper-event.so.1.02.1 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libext2fs.so.2 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libgcc_s.so.1 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/liblzma.so.5 \
@@ -99,11 +134,17 @@ COPY --from=debian /lib/${LIB_DIR_PREFIX}-linux-gnu/libselinux.so.1 \
                    /lib/${LIB_DIR_PREFIX}-linux-gnu/libzstd.so.1 /lib/${LIB_DIR_PREFIX}-linux-gnu/
 
 COPY --from=debian /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libblkid.so.1 \
+                   /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libsmartcols.so.1 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libbsd.so.0 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libinih.so.1 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libmount.so.1 \         
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libudev.so.1 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libuuid.so.1 \
+                   /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libzstd.so.1 \
+                   /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libaio.so.1 \
+                   /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libgcrypt.so.20 \
+                   /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libsystemd.so.0 \
+                   /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/liblz4.so.1 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libacl.so.1 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libattr.so.1 \
                    /usr/lib/${LIB_DIR_PREFIX}-linux-gnu/libedit.so.2 \
@@ -130,4 +171,5 @@ RUN /print-missing-deps.sh
 # Final build stage, create the real Docker image with ENTRYPOINT
 FROM output-image
 
-ENTRYPOINT ["/gce-pd-csi-driver"]
+COPY --from=builder /go/src/sigs.k8s.io/gcp-compute-persistent-disk-csi-driver/initialize-driver.sh /initialize-driver.sh
+ENTRYPOINT ["/initialize-driver.sh"]

cmd/gce-pd-csi-driver/main.go

@@ -29,7 +29,6 @@ import (
 
 	"k8s.io/klog/v2"
 	"k8s.io/utils/strings/slices"
-
 	"sigs.k8s.io/gcp-compute-persistent-disk-csi-driver/pkg/common"
 	"sigs.k8s.io/gcp-compute-persistent-disk-csi-driver/pkg/deviceutils"
 	gce "sigs.k8s.io/gcp-compute-persistent-disk-csi-driver/pkg/gce-cloud-provider/compute"
@@ -72,6 +71,8 @@ var (
 	formatAndMountTimeout       = flag.Duration("format-and-mount-timeout", 1*time.Minute, "The maximum duration of a format and mount operation before another such operation will be started. Used only if --serialize-format-and-mount")
 	fallbackRequisiteZonesFlag  = flag.String("fallback-requisite-zones", "", "Comma separated list of requisite zones that will be used if there are not sufficient zones present in requisite topologies when provisioning a disk")
 	enableStoragePoolsFlag      = flag.Bool("enable-storage-pools", false, "If set to true, the CSI Driver will allow volumes to be provisioned in Storage Pools")
+	enableDataCacheFlag         = flag.Bool("enable-data-cache", false, "If set to true, the CSI Driver will allow volumes to be provisioned with Data Cache configuration")
+	nodeName                    = flag.String("node-name", "", "The node this driver is running on")
 
 	multiZoneVolumeHandleDiskTypesFlag = flag.String("multi-zone-volume-handle-disk-types", "", "Comma separated list of allowed disk types that can use the multi-zone volumeHandle. Used only if --multi-zone-volume-handle-enable")
 	multiZoneVolumeHandleEnableFlag    = flag.Bool("multi-zone-volume-handle-enable", false, "If set to true, the multi-zone volumeHandle feature will be enabled")
@@ -122,7 +123,7 @@ func handle() {
 	if version == "" {
 		klog.Fatalf("version must be set at compile time")
 	}
-	klog.V(2).Infof("Driver vendor version %v", version)
+	klog.V(4).Infof("Driver vendor version %v", version)
 
 	// Start tracing as soon as possible
 	if *enableOtelTracing {
@@ -209,7 +210,7 @@ func handle() {
 		}
 		initialBackoffDuration := time.Duration(*errorBackoffInitialDurationMs) * time.Millisecond
 		maxBackoffDuration := time.Duration(*errorBackoffMaxDurationMs) * time.Millisecond
-		controllerServer = driver.NewControllerServer(gceDriver, cloudProvider, initialBackoffDuration, maxBackoffDuration, fallbackRequisiteZones, *enableStoragePoolsFlag, multiZoneVolumeHandleConfig, listVolumesConfig)
+		controllerServer = driver.NewControllerServer(gceDriver, cloudProvider, initialBackoffDuration, maxBackoffDuration, fallbackRequisiteZones, *enableStoragePoolsFlag, *enableDataCacheFlag, multiZoneVolumeHandleConfig, listVolumesConfig)
 	} else if *cloudConfigFilePath != "" {
 		klog.Warningf("controller service is disabled but cloud config given - it has no effect")
 	}
@@ -227,10 +228,29 @@ func handle() {
 		if err != nil {
 			klog.Fatalf("Failed to set up metadata service: %v", err.Error())
 		}
-		nodeServer = driver.NewNodeServer(gceDriver, mounter, deviceUtils, meta, statter)
+		isDataCacheEnabledNodePool, err := isDataCacheEnabledNodePool(ctx, *nodeName)
+		if err != nil {
+			klog.Fatalf("Failed to get node info from API server: %v", err.Error())
+		}
+		nsArgs := driver.NodeServerArgs{
+			EnableDataCache:          *enableDataCacheFlag,
+			DataCacheEnabledNodePool: isDataCacheEnabledNodePool,
+		}
+		nodeServer = driver.NewNodeServer(gceDriver, mounter, deviceUtils, meta, statter, nsArgs)
 		if *maxConcurrentFormatAndMount > 0 {
 			nodeServer = nodeServer.WithSerializedFormatAndMount(*formatAndMountTimeout, *maxConcurrentFormatAndMount)
 		}
+		if *enableDataCacheFlag {
+			if nodeName == nil || *nodeName == "" {
+				klog.Errorf("Data Cache enabled, but --node-name not passed")
+			}
+			if nsArgs.DataCacheEnabledNodePool {
+				if err := setupDataCache(ctx, *nodeName, nodeServer.MetadataService.GetName()); err != nil {
+					klog.Errorf("Data Cache setup failed: %v", err)
+				}
+				go driver.StartWatcher(*nodeName)
+			}
+		}
 	}
 
 	err = gceDriver.SetupGCEDriver(driverName, version, extraVolumeLabels, extraTags, identityServer, controllerServer, nodeServer)
@@ -311,3 +331,87 @@ func urlFlag(target **url.URL, name string, usage string) {
 		return err
 	})
 }
+
+func isDataCacheEnabledNodePool(ctx context.Context, nodeName string) (bool, error) {
+	if !*enableDataCacheFlag || nodeName == "" {
+		return false, nil
+	}
+	if nodeName != common.TestNode { // disregard logic below when E2E testing.
+		dataCacheLSSDCount, err := driver.GetDataCacheCountFromNodeLabel(ctx, nodeName)
+		return dataCacheLSSDCount != 0, err
+	} else if nodeName == common.TestNode {
+		return true, nil
+	}
+	return false, nil
+}
+
+func fetchLssdsForRaiding(lssdCount int) ([]string, error) {
+	allLssds, err := driver.FetchAllLssds()
+	if err != nil {
+		return nil, fmt.Errorf("Error listing all LSSDs %v", err)
+	}
+
+	raidedLssds, err := driver.FetchRaidedLssds()
+	if err != nil {
+		return nil, fmt.Errorf("Error listing RAIDed LSSDs %v", err)
+	}
+
+	LSSDsWithEmptyMountPoint, err := driver.FetchLSSDsWithEmptyMountPoint()
+	if err != nil {
+		return nil, fmt.Errorf("Error listing LSSDs with empty mountpoint: %v", err)
+	}
+
+	// We need to ensure the disks to be used for Data Cache are both unRAIDed & not containing mountpoints for ephemeral storage already
+	availableLssds := slices.Filter(nil, allLssds, func(e string) bool {
+		return slices.Contains(LSSDsWithEmptyMountPoint, e) && !slices.Contains(raidedLssds, e)
+	})
+
+	if len(availableLssds) == 0 {
+		return nil, fmt.Errorf("No LSSDs available to set up caching")
+	}
+
+	if len(availableLssds) < lssdCount {
+		return nil, fmt.Errorf("Not enough LSSDs available to set up caching. Available LSSDs: %v, wanted LSSDs: %v", len(availableLssds), lssdCount)
+	}
+
+	return availableLssds[:lssdCount], nil
+}
+
+func setupDataCache(ctx context.Context, nodeName string, nodeId string) error {
+	isAlreadyRaided, err := driver.IsRaided()
+	if err != nil {
+		klog.V(4).Infof("Errored while scanning for available LocalSSDs err:%v; continuing Raiding", err)
+	} else if isAlreadyRaided {
+		klog.V(4).Infof("Local SSDs are already RAIDed. Skipping Data Cache setup.")
+		return nil
+	}
+
+	lssdCount := common.LocalSSDCountForDataCache
+	if nodeName != common.TestNode {
+		var err error
+		lssdCount, err = driver.GetDataCacheCountFromNodeLabel(ctx, nodeName)
+		if err != nil {
+			return err
+		}
+		if lssdCount == 0 {
+			klog.V(4).Infof("Data Cache is not enabled on node %v, so skipping caching setup", nodeName)
+			return nil
+		}
+	}
+	lssdNames, err := fetchLssdsForRaiding(lssdCount)
+	if err != nil {
+		klog.Fatalf("Failed to get sufficient SSDs for Data Cache's caching setup: %v", err)
+	}
+	klog.V(4).Infof("Raiding local ssds to setup Data Cache: %v", lssdNames)
+	if err := driver.RaidLocalSsds(lssdNames); err != nil {
+		return fmt.Errorf("Failed to Raid local SSDs, unable to setup Data Cache, got error %v", err)
+	}
+
+	// Initializing data cache node (VG checks w/ raided lssd)
+	if err := driver.InitializeDataCacheNode(nodeId); err != nil {
+		return err
+	}
+
+	klog.V(4).Infof("LSSD caching is setup for the Data Cache enabled node %s", nodeName)
+	return nil
+}

deploy/kubernetes/base/controller/cluster_setup.yaml

@@ -199,6 +199,9 @@ rules:
     verbs:     ['use']
     resourceNames:
     - csi-gce-pd-node-psp
+  - apiGroups: [""]
+    resources: ["nodes"]
+    verbs: ["get", "list"]
 ---
 
 kind: ClusterRole

deploy/kubernetes/base/controller/controller.yaml

@@ -139,6 +139,7 @@ spec:
           args:
             - "--v=5"
             - "--endpoint=unix:/csi/csi.sock"
+            - --enable-data-cache
           env:
             - name: GOOGLE_APPLICATION_CREDENTIALS
               value: "/etc/cloud-sa/cloud-sa.json"

deploy/kubernetes/base/node_linux/node.yaml

@@ -46,8 +46,15 @@ spec:
             - "--v=5"
             - "--endpoint=unix:/csi/csi.sock"
             - "--run-controller-service=false"
+            - "--enable-data-cache"
+            - "--node-name=$(KUBE_NODE_NAME)"
           securityContext:
             privileged: true
+          env:
+            - name: KUBE_NODE_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: spec.nodeName
           volumeMounts:
             - name: kubelet-dir
               mountPath: /var/lib/kubelet
@@ -66,6 +73,8 @@ spec:
               mountPath: /run/udev
             - name: sys
               mountPath: /sys
+            - name: lib-modules
+              mountPath: /lib/modules
       volumes:
         - name: registration-dir
           hostPath:
@@ -101,6 +110,10 @@ spec:
           hostPath:
             path: /sys
             type: Directory
+        - name: lib-modules
+          hostPath:
+            path: /lib/modules
+            type: Directory
       # https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/
       # See "special case". This will tolerate everything. Node component should
       # be scheduled on all nodes.

deploy/kubernetes/images/stable-master/image.yaml

@@ -49,8 +49,7 @@ metadata:
   name: imagetag-gcepd-driver
 imageTag:
   name: gke.gcr.io/gcp-compute-persistent-disk-csi-driver
-  # Don't change stable image without changing pdImagePlaceholder in
-  # test/k8s-integration/main.go
+  # pdImagePlaceholder in test/k8s-integration/main.go is updated automatically with the newTag
   newName: registry.k8s.io/cloud-provider-gcp/gcp-compute-persistent-disk-csi-driver
-  newTag: "v1.13.2"
+  newTag: "v1.13.3"
 ---

go.mod

@@ -57,8 +57,8 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/emicklei/go-restful v2.9.5+incompatible // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
-	github.com/fsnotify/fsnotify v1.5.4 // indirect
-	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/fsnotify/fsnotify v1.8.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-openapi/jsonpointer v0.20.0 // indirect
 	github.com/go-openapi/jsonreference v0.19.6 // indirect

go.sum

@@ -1029,8 +1029,8 @@ github.com/frankban/quicktest v1.8.1/go.mod h1:ui7WezCLWMWxVWr1GETZY3smRy0G4KWq9
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/fsnotify/fsnotify v1.5.1/go.mod h1:T3375wBYaZdLLcVNkcVbzGHY7f1l/uK5T5Ai1i3InKU=
-github.com/fsnotify/fsnotify v1.5.4 h1:jRbGcIw6P2Meqdwuo0H1p6JVLbL5DHKAKlYndzMwVZI=
-github.com/fsnotify/fsnotify v1.5.4/go.mod h1:OVB6XrOHzAwXMpEM7uPOzcehqUV2UqJxmVXmkdnm1bU=
+github.com/fsnotify/fsnotify v1.8.0 h1:dAwr6QBTBZIkG8roQaJjGof0pp0EeF+tNV7YBP3F/8M=
+github.com/fsnotify/fsnotify v1.8.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
 github.com/fsouza/fake-gcs-server v0.0.0-20180612165233-e85be23bdaa8/go.mod h1:1/HufuJ+eaDf4KTnYdS6HJMGvMRU8d4cYTuu/1QaBbI=
 github.com/fsouza/fake-gcs-server v1.19.4/go.mod h1:I0/88nHCASqJJ5M7zVF0zKODkYTcuXFW5J5yajsNJnE=
 github.com/fvbommel/sortorder v1.0.1/go.mod h1:uk88iVf1ovNn1iLfgUVU2F9o5eO30ui720w+kxuqRs0=
@@ -1071,8 +1071,8 @@ github.com/go-logr/logr v0.2.0/go.mod h1:z6/tIYblkpsD+a4lm/fGIIU9mZ+XfAiaFtq7xTg
 github.com/go-logr/logr v0.4.0/go.mod h1:z6/tIYblkpsD+a4lm/fGIIU9mZ+XfAiaFtq7xTgseGU=
 github.com/go-logr/logr v1.2.0/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
-github.com/go-logr/logr v1.4.1 h1:pKouT5E8xu9zeFC39JXRDukb6JFQPXM5p5I91188VAQ=
-github.com/go-logr/logr v1.4.1/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
+github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/go-logr/zapr v0.1.0/go.mod h1:tabnROwaDl0UNxkVeFRbY8bwB37GwRv0P8lg6aAiEnk=

initialize-driver.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+/bin/cp -r /lvm-tmp/lvm /etc/
+/bin/sed -i -e "s/.*allow_mixed_block_sizes = 0.*/	allow_mixed_block_sizes = 1/" /etc/lvm/lvm.conf
+/bin/sed -i -e "s/.*udev_sync = 1.*/	udev_sync = 0/" /etc/lvm/lvm.conf
+/bin/sed -i -e "s/.*udev_rules = 1.*/	udev_rules = 0/" /etc/lvm/lvm.conf
+/bin/sed -i -e "s/.*locking_dir = .*/	 locking_dir = \"\/tmp\"/" /etc/lvm/lvm.conf
+
+/gce-pd-csi-driver "$@"

pkg/common/constants.go

@@ -32,6 +32,25 @@ const (
 
 	// Label that is set on a disk when it is used by a 'multi-zone' VolumeHandle
 	MultiZoneLabel = "goog-gke-multi-zone"
+
+	// Data cache mode
+	DataCacheModeWriteBack    = "writeback"
+	DataCacheModeWriteThrough = "writethrough"
+
+	ContextDataCacheSize = "data-cache-size"
+	ContextDataCacheMode = "data-cache-mode"
+
+	// Keys in the publish context
+	ContexLocalSsdCacheSize = "local-ssd-cache-size"
+	// Node name for E2E tests
+	TestNode = "test-node-csi-e2e"
+
+	// Default LSSD count for datacache E2E tests
+	LocalSSDCountForDataCache = 2
+
+	// Node label for Data Cache (only applicable to GKE nodes)
+	NodeLabelPrefix         = "cloud.google.com/%s"
+	DataCacheLssdCountLabel = "gke-data-cache-disk"
 )
 
 // doc https://cloud.google.com/compute/docs/disks/hyperdisks#max-total-disks-per-vm