diff --git a/enterprise/server/raft/driver/driver.go b/enterprise/server/raft/driver/driver.go
index 61073340ac3..65d0693462f 100644
--- a/enterprise/server/raft/driver/driver.go
+++ b/enterprise/server/raft/driver/driver.go
@@ -7,7 +7,6 @@ import (
 	"flag"
 	"math"
 	"slices"
-	"sort"
 	"sync"
 	"time"
 
@@ -20,8 +19,8 @@ import (
 )
 
 var (
-	enableDriver           = flag.Bool("cache.raft.enable_driver", true, "If true, enable placement driver")
-	minNumReplicasPerRange = flag.Int("cache.raft.min_num_replicas_per_range", 3, "The minimum number of replicas each range should have")
+	enableDriver        = flag.Bool("cache.raft.enable_driver", true, "If true, enable placement driver")
+	minReplicasPerRange = flag.Int("cache.raft.min_replicas_per_range", 3, "The minimum number of replicas each range should have")
 )
 
 type DriverAction int
@@ -31,7 +30,7 @@ const (
 	DriverNoop
 	DriverRemoveReplica
 	DriverRemoveDeadReplica
-	DirverAddReplica
+	DriverAddReplica
 	DriverReplaceDeadReplica
 	DriverConsiderRebalance
 )
@@ -55,7 +54,7 @@ func (a DriverAction) Priority() float64 {
 	switch a {
 	case DriverReplaceDeadReplica:
 		return 400
-	case DirverAddReplica:
+	case DriverAddReplica:
 		return 300
 	case DriverRemoveDeadReplica:
 		return 200
@@ -69,6 +68,25 @@ func (a DriverAction) Priority() float64 {
 	}
 }
 
+func (a DriverAction) String() string {
+	switch a {
+	case DriverNoop:
+		return "no-op"
+	case DriverRemoveReplica:
+		return "remove-replica"
+	case DriverRemoveDeadReplica:
+		return "remove-dead-replica"
+	case DriverAddReplica:
+		return "add-replica"
+	case DriverReplaceDeadReplica:
+		return "replace-dead-replica"
+	case DriverConsiderRebalance:
+		return "consider-rebalance"
+	default:
+		return "unknown"
+	}
+}
+
 type IReplica interface {
 	RangeDescriptor() *rfpb.RangeDescriptor
 	ReplicaID() uint64
@@ -82,33 +100,40 @@ type IStore interface {
 	RemoveReplica(ctx context.Context, req *rfpb.RemoveReplicaRequest) (*rfpb.RemoveReplicaResponse, error)
 }
 
+// computeQuorum computes a quorum, which a majority of members from a peer set.
+// In raft, when a quorum of nodes is unavailable, the cluster becomes
+// unavailable.
 func computeQuorum(numNodes int) int {
 	return (numNodes / 2) + 1
 }
 
-func (rq *ReplicateQueue) computeAction(replicas []*rfpb.ReplicaDescriptor) (DriverAction, float64) {
+// computeAction computes the action needed and its priority.
+func (rq *Queue) computeAction(replicas []*rfpb.ReplicaDescriptor) (DriverAction, float64) {
 	if rq.storeMap == nil {
 		action := DriverNoop
 		return action, action.Priority()
 	}
 	curReplicas := len(replicas)
-	desiredQuorum := computeQuorum(*minNumReplicasPerRange)
+	desiredQuorum := computeQuorum(*minReplicasPerRange)
 	quorum := computeQuorum(curReplicas)
 
-	if curReplicas < *minNumReplicasPerRange {
-		action := DirverAddReplica
+	if curReplicas < *minReplicasPerRange {
+		action := DriverAddReplica
 		adjustedPriority := action.Priority() + float64(desiredQuorum-curReplicas)
 		return action, adjustedPriority
 	}
 	replicasByStatus := rq.storeMap.DivideByStatus(replicas)
 	numLiveReplicas := len(replicasByStatus.LiveReplicas) + len(replicasByStatus.SuspectReplicas)
 	numDeadReplicas := len(replicasByStatus.DeadReplicas)
+
 	if numLiveReplicas < quorum {
+		// The cluster is unavailable since we don't have enough live nodes.
+		// There is no point of doing anything right now.
 		action := DriverNoop
 		return action, action.Priority()
 	}
 
-	if curReplicas <= *minNumReplicasPerRange && numDeadReplicas > 0 {
+	if curReplicas <= *minReplicasPerRange && numDeadReplicas > 0 {
 		action := DriverReplaceDeadReplica
 		return action, action.Priority()
 	}
@@ -118,7 +143,7 @@ func (rq *ReplicateQueue) computeAction(replicas []*rfpb.ReplicaDescriptor) (Dri
 		return action, action.Priority()
 	}
 
-	if curReplicas > *minNumReplicasPerRange {
+	if curReplicas > *minReplicasPerRange {
 		action := DriverRemoveDeadReplica
 		ajustedPriority := action.Priority() - float64(curReplicas%2)
 		return action, ajustedPriority
@@ -134,7 +159,7 @@ type pqItem struct {
 
 	priority   float64
 	insertTime time.Time
-	// The index is needed by update and is maintained by the heap.Interface methods.
+
 	index      int // The index of the item in the heap.
 	processing bool
 	requeue    bool
@@ -178,7 +203,9 @@ func (pq *priorityQueue) getItemWithMinPriority() *pqItem {
 	return old[n-1]
 }
 
-type ReplicateQueue struct {
+// The Queue is responsible for up-replicate, down-replicate and reblance ranges
+// across the stores.
+type Queue struct {
 	pq       *priorityQueue
 	storeMap *storemap.StoreMap
 	store    IStore
@@ -191,9 +218,9 @@ type ReplicateQueue struct {
 	started bool
 }
 
-func NewReplicateQueue(store IStore, gossipManager interfaces.GossipService) *ReplicateQueue {
+func NewQueue(store IStore, gossipManager interfaces.GossipService) *Queue {
 	storeMap := storemap.New(gossipManager)
-	return &ReplicateQueue{
+	return &Queue{
 		storeMap: storeMap,
 		pq:       &priorityQueue{},
 		store:    store,
@@ -201,7 +228,7 @@ func NewReplicateQueue(store IStore, gossipManager interfaces.GossipService) *Re
 	}
 }
 
-func (rq *ReplicateQueue) shouldQueue(repl IReplica) (bool, float64) {
+func (rq *Queue) shouldQueue(repl IReplica) (bool, float64) {
 	rd := repl.RangeDescriptor()
 
 	if !rq.store.HaveLease(rd.GetRangeId()) {
@@ -221,7 +248,10 @@ func (rq *ReplicateQueue) shouldQueue(repl IReplica) (bool, float64) {
 	return false, 0
 }
 
-func (rq *ReplicateQueue) MaybeAdd(replica IReplica) {
+// MaybeAdd adds a replica to the queue if the store has the lease for the range,
+// and there is work needs to be done.
+// When the queue is full, it deletes the least important replica from the queue.
+func (rq *Queue) MaybeAdd(replica IReplica) {
 	shouldQueue, priority := rq.shouldQueue(replica)
 	if !shouldQueue {
 		return
@@ -260,7 +290,7 @@ func (rq *ReplicateQueue) MaybeAdd(replica IReplica) {
 	}
 }
 
-func (rq *ReplicateQueue) remove(item *pqItem) {
+func (rq *Queue) remove(item *pqItem) {
 	if item.processing {
 		item.requeue = false
 		return
@@ -271,7 +301,7 @@ func (rq *ReplicateQueue) remove(item *pqItem) {
 	rq.pqItemMap.Delete(item.shardID)
 }
 
-func (rq *ReplicateQueue) Start() {
+func (rq *Queue) Start() {
 	rq.mu.Lock()
 	started := rq.started
 	rq.mu.Unlock()
@@ -316,7 +346,7 @@ func (rq *ReplicateQueue) Start() {
 	}
 }
 
-func (rq *ReplicateQueue) Stop() {
+func (rq *Queue) Stop() {
 	rq.mu.Lock()
 	defer rq.mu.Unlock()
 	if !rq.started {
@@ -326,6 +356,7 @@ func (rq *ReplicateQueue) Stop() {
 	rq.started = false
 }
 
+// findReplacingReplica finds a dead replica to be removed.
 func findReplacingReplica(replicas []*rfpb.ReplicaDescriptor, replicaByStatus *storemap.ReplicasByStatus) *rfpb.ReplicaDescriptor {
 	if len(replicaByStatus.DeadReplicas) == 0 {
 		// nothing to be removed
@@ -349,13 +380,12 @@ func storeHasReplica(node *rfpb.NodeDescriptor, existing []*rfpb.ReplicaDescript
 	return false
 }
 
-func (rq *ReplicateQueue) allocateTarget(existing []*rfpb.ReplicaDescriptor) *rfpb.NodeDescriptor {
+// allocateTarget finds a target node for rd to up-replicate.
+func (rq *Queue) allocateTarget(rd *rfpb.RangeDescriptor) *rfpb.NodeDescriptor {
 	storesWithStats := rq.storeMap.GetStoresWithStats()
-	// Rank stores
-	// check free bytes
 	var candidates []*candidate
 	for _, su := range storesWithStats.Usages {
-		if storeHasReplica(su.GetNode(), existing) {
+		if storeHasReplica(su.GetNode(), rd.GetReplicas()) {
 			continue
 		}
 		candidates = append(candidates, &candidate{
@@ -368,7 +398,6 @@ func (rq *ReplicateQueue) allocateTarget(existing []*rfpb.ReplicaDescriptor) *rf
 	if len(candidates) == 0 {
 		return nil
 	}
-	sort.Sort(sort.Reverse(byScore(candidates)))
 	slices.SortFunc(candidates, func(a, b *candidate) int {
 		if n := a.compare(b); n != 0 {
 			if n < 0 {
@@ -388,8 +417,8 @@ type change struct {
 	removeOp *rfpb.RemoveReplicaRequest
 }
 
-func (rq *ReplicateQueue) addReplica(rd *rfpb.RangeDescriptor) *change {
-	target := rq.allocateTarget(rd.GetReplicas())
+func (rq *Queue) addReplica(rd *rfpb.RangeDescriptor) *change {
+	target := rq.allocateTarget(rd)
 	if target == nil {
 		log.Debugf("cannot find targets for range descriptor:%+v", rd)
 		return nil
@@ -403,7 +432,7 @@ func (rq *ReplicateQueue) addReplica(rd *rfpb.RangeDescriptor) *change {
 	}
 }
 
-func (rq *ReplicateQueue) replaceDeadReplica(rd *rfpb.RangeDescriptor, replicasByStatus *storemap.ReplicasByStatus) *change {
+func (rq *Queue) replaceDeadReplica(rd *rfpb.RangeDescriptor, replicasByStatus *storemap.ReplicasByStatus) *change {
 	replacing := findReplacingReplica(rd.GetReplicas(), replicasByStatus)
 	if replacing == nil {
 		// nothing to remove
@@ -419,7 +448,7 @@ func (rq *ReplicateQueue) replaceDeadReplica(rd *rfpb.RangeDescriptor, replicasB
 	return change
 }
 
-func (rq *ReplicateQueue) applyChange(ctx context.Context, change *change) error {
+func (rq *Queue) applyChange(ctx context.Context, change *change) error {
 	var rd *rfpb.RangeDescriptor
 	if change.addOp != nil {
 		rsp, err := rq.store.AddReplica(ctx, change.addOp)
@@ -445,7 +474,7 @@ func (rq *ReplicateQueue) applyChange(ctx context.Context, change *change) error
 
 }
 
-func (rq *ReplicateQueue) processReplica(repl IReplica) (bool, error) {
+func (rq *Queue) processReplica(repl IReplica) (bool, error) {
 	rd := repl.RangeDescriptor()
 	if !rq.store.HaveLease(rd.GetRangeId()) {
 		// the store doesn't have the lease of this range.
@@ -460,7 +489,7 @@ func (rq *ReplicateQueue) processReplica(repl IReplica) (bool, error) {
 
 	switch action {
 	case DriverNoop:
-	case DirverAddReplica:
+	case DriverAddReplica:
 		log.Debugf("add replica: %d", repl.ShardID())
 		change = rq.addReplica(rd)
 	case DriverReplaceDeadReplica:
@@ -493,7 +522,7 @@ func (rq *ReplicateQueue) processReplica(repl IReplica) (bool, error) {
 	return true, err
 }
 
-func (rq *ReplicateQueue) postProcess(repl IReplica) {
+func (rq *Queue) postProcess(repl IReplica) {
 	itemIface, ok := rq.pqItemMap.Load(repl.ShardID())
 	if !ok {
 		alert.UnexpectedEvent("unexpected_pq_item_not_found")
@@ -552,18 +581,6 @@ func (c *candidate) compare(o *candidate) float64 {
 	return 0
 }
 
-type byScore []*candidate
-
-func (x byScore) Len() int { return len(x) }
-func (x byScore) Less(i, j int) bool {
-	res := x[i].compare(x[j])
-	if res != 0 {
-		return res < 0
-	}
-	return x[i].usage.GetNode().GetNhid() < x[j].usage.GetNode().GetNhid()
-}
-func (x byScore) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
-
 func replicaCountMeanLevel(storesWithStats *storemap.StoresWithStats, su *rfpb.StoreUsage) meanLevel {
 	maxReplicaCount := aboveMeanReplicaCountThreshold(storesWithStats.ReplicaCount.Mean)
 	minReplicaCount := belowMeanReplicaCountThreshold(storesWithStats.ReplicaCount.Mean)
diff --git a/enterprise/server/raft/store/store.go b/enterprise/server/raft/store/store.go
index 2a9c433a396..d94dfe09d2a 100644
--- a/enterprise/server/raft/store/store.go
+++ b/enterprise/server/raft/store/store.go
@@ -107,7 +107,7 @@ type Store struct {
 	updateTagsWorker *updateTagsWorker
 	txnCoordinator   *txn.Coordinator
 
-	replicateQueue *driver.ReplicateQueue
+	driverQueue *driver.Queue
 }
 
 // registryHolder implements NodeRegistryFactory. When nodeHost is created, it
@@ -208,7 +208,7 @@ func NewWithArgs(env environment.Env, rootDir string, nodeHost *dragonboat.NodeH
 
 	usages, err := usagetracker.New(s, gossipManager, s.NodeDescriptor(), partitions, s.AddEventListener())
 
-	s.replicateQueue = driver.NewReplicateQueue(s, gossipManager)
+	s.driverQueue = driver.NewQueue(s, gossipManager)
 
 	if err != nil {
 		return nil, err
@@ -436,7 +436,7 @@ func (s *Store) Start() error {
 		return nil
 	})
 	eg.Go(func() error {
-		s.replicateQueue.Start()
+		s.driverQueue.Start()
 		return nil
 	})
 
@@ -454,7 +454,7 @@ func (s *Store) Stop(ctx context.Context) error {
 		s.egCancel()
 		s.leaseKeeper.Stop()
 		s.liveness.Release()
-		s.replicateQueue.Stop()
+		s.driverQueue.Stop()
 		s.eg.Wait()
 	}
 	s.updateTagsWorker.Stop()
@@ -1855,7 +1855,7 @@ func (store *Store) scan(ctx context.Context) {
 		log.Debug("scan started")
 		replicas := store.getLeasedReplicas()
 		for _, repl := range replicas {
-			store.replicateQueue.MaybeAdd(repl)
+			store.driverQueue.MaybeAdd(repl)
 		}
 	}
 }