diff --git a/blobstore/api/blobnode/datainfo.go b/blobstore/api/blobnode/datainfo.go
index 62f998395..a2c0a5b4a 100644
--- a/blobstore/api/blobnode/datainfo.go
+++ b/blobstore/api/blobnode/datainfo.go
@@ -28,6 +28,8 @@ type DiskHeartBeatInfo struct {
 	MaxChunkCnt  int64        `json:"max_chunk_cnt"`  // note: maintained by clustermgr
 	FreeChunkCnt int64        `json:"free_chunk_cnt"` // note: maintained by clustermgr
 	UsedChunkCnt int64        `json:"used_chunk_cnt"` // current number of chunks on the disk
+
+	OversoldFreeChunkCnt int64 `json:"oversold_free_chunk_cnt"` // note: maintained by clustermgr
 }
 
 type DiskInfo struct {
diff --git a/blobstore/api/clustermgr/disk.go b/blobstore/api/clustermgr/disk.go
index 30266ef01..763dd90a6 100644
--- a/blobstore/api/clustermgr/disk.go
+++ b/blobstore/api/clustermgr/disk.go
@@ -68,18 +68,19 @@ type DiskHeartbeatRet struct {
 }
 
 type DiskStatInfo struct {
-	IDC            string `json:"idc"`
-	Total          int    `json:"total"`
-	TotalChunk     int64  `json:"total_chunk"`
-	TotalFreeChunk int64  `json:"total_free_chunk"`
-	Available      int    `json:"available"`
-	Readonly       int    `json:"readonly"`
-	Expired        int    `json:"expired"`
-	Broken         int    `json:"broken"`
-	Repairing      int    `json:"repairing"`
-	Repaired       int    `json:"repaired"`
-	Dropping       int    `json:"dropping"`
-	Dropped        int    `json:"dropped"`
+	IDC                    string `json:"idc"`
+	Total                  int    `json:"total"`
+	TotalChunk             int64  `json:"total_chunk"`
+	TotalFreeChunk         int64  `json:"total_free_chunk"`
+	TotalOversoldFreeChunk int64  `json:"total_oversold_free_chunk"`
+	Available              int    `json:"available"`
+	Readonly               int    `json:"readonly"`
+	Expired                int    `json:"expired"`
+	Broken                 int    `json:"broken"`
+	Repairing              int    `json:"repairing"`
+	Repaired               int    `json:"repaired"`
+	Dropping               int    `json:"dropping"`
+	Dropped                int    `json:"dropped"`
 }
 
 type SpaceStatInfo struct {
diff --git a/blobstore/clustermgr/diskmgr/alloc.go b/blobstore/clustermgr/diskmgr/alloc.go
index dd4462748..622a35314 100644
--- a/blobstore/clustermgr/diskmgr/alloc.go
+++ b/blobstore/clustermgr/diskmgr/alloc.go
@@ -316,7 +316,11 @@ func (d *blobNodeAllocator) allocDisk(ctx context.Context, excludes map[proto.Di
 			disk := disks[randNum]
 			disk.lock.RLock()
 			defer disk.lock.RUnlock()
+
 			freeChunk := disk.info.FreeChunkCnt
+			if disk.info.OversoldFreeChunkCnt > disk.info.FreeChunkCnt {
+				freeChunk = disk.info.OversoldFreeChunkCnt
+			}
 			if freeChunk <= 0 {
 				return nil
 			}
@@ -372,7 +376,12 @@ func (s *idcAllocator) alloc(ctx context.Context, count int, excludes map[proto.
 	}
 	for id := range chosenDisks {
 		chosenDisks[id].lock.Lock()
-		chosenDisks[id].info.FreeChunkCnt -= 1
+		if chosenDisks[id].info.FreeChunkCnt > 0 {
+			chosenDisks[id].info.FreeChunkCnt -= 1
+		}
+		if chosenDisks[id].info.OversoldFreeChunkCnt > 0 {
+			chosenDisks[id].info.OversoldFreeChunkCnt -= 1
+		}
 		chosenDisks[id].lock.Unlock()
 		ret = append(ret, id)
 	}
diff --git a/blobstore/clustermgr/diskmgr/alloc_test.go b/blobstore/clustermgr/diskmgr/alloc_test.go
index 8e2bdf42e..7a8256d74 100644
--- a/blobstore/clustermgr/diskmgr/alloc_test.go
+++ b/blobstore/clustermgr/diskmgr/alloc_test.go
@@ -45,6 +45,7 @@ var testDiskMgrConfig = DiskMgrConfig{
 	FlushIntervalS:           300,
 	ChunkSize:                17179869184, // 16G
 	CodeModes:                []codemode.CodeMode{codemode.EC15P12, codemode.EC6P6},
+	ChunkOversoldRatio:       0.5,
 	CopySetConfigs:           make(map[proto.NodeRole]map[proto.DiskType]CopySetConfig),
 }
 
diff --git a/blobstore/clustermgr/diskmgr/diskmgr.go b/blobstore/clustermgr/diskmgr/diskmgr.go
index 2583c8a58..084c10581 100644
--- a/blobstore/clustermgr/diskmgr/diskmgr.go
+++ b/blobstore/clustermgr/diskmgr/diskmgr.go
@@ -130,6 +130,7 @@ type DiskMgrConfig struct {
 	IDC                      []string            `json:"-"`
 	CodeModes                []codemode.CodeMode `json:"-"`
 	ChunkSize                int64               `json:"-"`
+	ChunkOversoldRatio       float64             `json:"-"`
 
 	CopySetConfigs map[proto.NodeRole]map[proto.DiskType]CopySetConfig `json:"copy_set_configs"`
 }
@@ -974,6 +975,9 @@ func (d *DiskMgr) heartBeatDiskInfo(ctx context.Context, infos []*blobnode.DiskH
 		diskInfo.info.MaxChunkCnt = info.Size / d.ChunkSize
 		// use the minimum value as free chunk count
 		diskInfo.info.FreeChunkCnt = diskInfo.info.MaxChunkCnt - diskInfo.info.UsedChunkCnt
+		if d.ChunkOversoldRatio > 0 {
+			diskInfo.info.OversoldFreeChunkCnt = int64(float64(diskInfo.info.MaxChunkCnt)*(1+d.ChunkOversoldRatio)) - diskInfo.info.UsedChunkCnt
+		}
 		freeChunkCnt := info.Free / d.ChunkSize
 		if freeChunkCnt < diskInfo.info.FreeChunkCnt {
 			span.Debugf("use minimum free chunk count, disk id[%d], free chunk[%d]", diskInfo.diskID, freeChunkCnt)
diff --git a/blobstore/clustermgr/diskmgr/diskmgr_test.go b/blobstore/clustermgr/diskmgr/diskmgr_test.go
index 7b7950161..7dc3603c0 100644
--- a/blobstore/clustermgr/diskmgr/diskmgr_test.go
+++ b/blobstore/clustermgr/diskmgr/diskmgr_test.go
@@ -193,7 +193,7 @@ func TestDiskMgr_Heartbeat(t *testing.T) {
 	for i := 1; i <= 10; i++ {
 		diskInfo, err := testDiskMgr.GetDiskInfo(ctx, proto.DiskID(i))
 		require.NoError(t, err)
-		diskInfo.DiskHeartBeatInfo.Free = 0
+		// diskInfo.DiskHeartBeatInfo.Free = 0
 		diskInfo.DiskHeartBeatInfo.FreeChunkCnt = 0
 		heartbeatInfos = append(heartbeatInfos, &diskInfo.DiskHeartBeatInfo)
 	}
@@ -205,7 +205,7 @@ func TestDiskMgr_Heartbeat(t *testing.T) {
 		diskInfo, err := testDiskMgr.GetDiskInfo(ctx, proto.DiskID(i))
 		require.NoError(t, err)
 		require.Equal(t, diskInfo.Free/testDiskMgr.ChunkSize, diskInfo.FreeChunkCnt)
-		require.Equal(t, int64(0), diskInfo.Free)
+		require.Greater(t, diskInfo.OversoldFreeChunkCnt, diskInfo.FreeChunkCnt)
 	}
 
 	// get heartbeat change disk
diff --git a/blobstore/clustermgr/diskmgr/refresh.go b/blobstore/clustermgr/diskmgr/refresh.go
index e60cd627d..e0301a81e 100644
--- a/blobstore/clustermgr/diskmgr/refresh.go
+++ b/blobstore/clustermgr/diskmgr/refresh.go
@@ -192,7 +192,10 @@ func (d *DiskMgr) generateDiskSetStorage(ctx context.Context, disks []*diskItem,
 			rack = node.info.Rack
 			host = node.info.Host
 		}
-		freeChunk := disk.info.FreeChunkCnt
+		originalFreeChunk, freeChunk := disk.info.FreeChunkCnt, disk.info.FreeChunkCnt
+		if disk.info.OversoldFreeChunkCnt > freeChunk {
+			freeChunk = disk.info.OversoldFreeChunkCnt
+		}
 		maxChunk := disk.info.MaxChunkCnt
 		readonly := disk.info.Readonly
 		size := disk.info.Size
@@ -207,7 +210,8 @@ func (d *DiskMgr) generateDiskSetStorage(ctx context.Context, disks []*diskItem,
 		}
 		diskStatInfosM[idc].Total += 1
 		diskStatInfosM[idc].TotalChunk += maxChunk
-		diskStatInfosM[idc].TotalFreeChunk += freeChunk
+		diskStatInfosM[idc].TotalFreeChunk += originalFreeChunk
+		diskStatInfosM[idc].TotalOversoldFreeChunk += freeChunk
 		if readonly {
 			diskStatInfosM[idc].Readonly += 1
 		}
diff --git a/blobstore/clustermgr/svr.go b/blobstore/clustermgr/svr.go
index 968073cf8..dd8cecd22 100644
--- a/blobstore/clustermgr/svr.go
+++ b/blobstore/clustermgr/svr.go
@@ -402,6 +402,17 @@ func (c *Config) checkAndFix() (err error) {
 	if c.ClusterCfg[proto.VolumeReserveSizeKey] == nil {
 		c.ClusterCfg[proto.VolumeReserveSizeKey] = DefaultVolumeReserveSize
 	}
+	if c.ClusterCfg[proto.VolumeOverboughtRatioKey] != nil || c.ClusterCfg[proto.ChunkOversoldRatioKey] != nil {
+		volumeOverboughtRatio, _ := strconv.ParseFloat(c.ClusterCfg[proto.VolumeOverboughtRatioKey].(string), 64)
+		chunkOversoldRatio, _ := strconv.ParseFloat(c.ClusterCfg[proto.ChunkOversoldRatioKey].(string), 64)
+
+		if chunkOversoldRatio < 0.5*volumeOverboughtRatio || chunkOversoldRatio > volumeOverboughtRatio {
+			return errors.New("ChunkOversoldRatio must be between 0.5*VolumeOverboughtRatioKey and VolumeOverboughtRatioKey")
+		}
+		c.VolumeMgrConfig.VolumeOverboughtRatio = volumeOverboughtRatio
+		c.DiskMgrConfig.ChunkOversoldRatio = chunkOversoldRatio
+	}
+
 	c.VolumeMgrConfig.ChunkSize = c.ChunkSize
 	c.DiskMgrConfig.ChunkSize = int64(c.ChunkSize)
 	c.ClusterCfg[proto.VolumeChunkSizeKey] = c.ChunkSize
diff --git a/blobstore/clustermgr/volumemgr/startup.go b/blobstore/clustermgr/volumemgr/startup.go
index b62cd9545..663282221 100644
--- a/blobstore/clustermgr/volumemgr/startup.go
+++ b/blobstore/clustermgr/volumemgr/startup.go
@@ -65,6 +65,8 @@ type VolumeMgrConfig struct {
 	CodeModePolicies []codemode.Policy `json:"-"`
 	Region           string            `json:"-"`
 	ClusterID        proto.ClusterID   `json:"-"`
+
+	VolumeOverboughtRatio float64 `json:"-"`
 }
 
 func (c *VolumeMgrConfig) checkAndFix() {
diff --git a/blobstore/clustermgr/volumemgr/volumeunit.go b/blobstore/clustermgr/volumemgr/volumeunit.go
index 76389c7b8..d87cec98a 100644
--- a/blobstore/clustermgr/volumemgr/volumeunit.go
+++ b/blobstore/clustermgr/volumemgr/volumeunit.go
@@ -309,12 +309,20 @@ func (v *VolumeMgr) applyChunkReport(ctx context.Context, chunks *cmapi.ReportCh
 		vol.vUnits[idx].vuInfo.Total = chunk.Total
 
 		dataChunkNum := uint64(v.codeMode[vol.volInfoBase.CodeMode].tactic.N)
-		volFree := vol.vUnits[idx].vuInfo.Free * dataChunkNum
 		volUsed := vol.vUnits[idx].vuInfo.Used * dataChunkNum
 		volTotal := vol.vUnits[idx].vuInfo.Total * dataChunkNum
+		volFree := vol.vUnits[idx].vuInfo.Free * dataChunkNum
+		if v.VolumeOverboughtRatio > 0 {
+			volFree = 0
+			_volTotal := uint64(float64(volTotal) * v.VolumeOverboughtRatio)
+			if _volTotal > volUsed {
+				volFree = _volTotal - volUsed
+			}
+		}
 
 		// use the minimum free size as volume free
-		if vol.volInfoBase.Free > volFree {
+		// or use calculated free size when overboughtRatio is specified as overboughtRatio may set into larger value
+		if vol.volInfoBase.Free > volFree || v.VolumeOverboughtRatio > 0 {
 			vol.volInfoBase.Used = volUsed
 			vol.volInfoBase.Total = volTotal
 			vol.smallestVUIdx = idx
diff --git a/blobstore/clustermgr/volumemgr/volumeunit_test.go b/blobstore/clustermgr/volumemgr/volumeunit_test.go
index 7bd20e5ed..84b8ec745 100644
--- a/blobstore/clustermgr/volumemgr/volumeunit_test.go
+++ b/blobstore/clustermgr/volumemgr/volumeunit_test.go
@@ -382,14 +382,20 @@ func TestVolumeMgr_applyChunkReport(t *testing.T) {
 			Vuid:  vuid,
 			Total: defaultChunkSize + 1,
 			Free:  uint64(1024 * 1024),
-			Used:  defaultChunkSize - uint64(1024*i),
+			Used:  defaultChunkSize - uint64(1024*1024),
 		}
 		args = append(args, chunk)
 	}
-	// set  report chunkInfo(vid:1) epoch=2,
+	// set report chunkInfo(vid:1) epoch=2,
 	args[1].Vuid = proto.EncodeVuid(proto.EncodeVuidPrefix(proto.Vid(1), 2), 0)
 	err := mockVolumeMgr.applyChunkReport(context.Background(), &clustermgr.ReportChunkArgs{ChunkInfos: args})
 	require.NoError(t, err)
+
+	// validate volume info
+	vol := mockVolumeMgr.all.getVol(args[0].Vuid.Vid())
+	dataChunkNum := uint64(mockVolumeMgr.codeMode[vol.volInfoBase.CodeMode].tactic.N)
+	require.Equal(t, args[0].Free*dataChunkNum, vol.volInfoBase.Free)
+
 	for i := 0; i < len(args); i++ {
 		vol := mockVolumeMgr.all.getVol(args[i].Vuid.Vid())
 		unit := vol.vUnits[args[i].Vuid.Index()]
@@ -408,6 +414,43 @@ func TestVolumeMgr_applyChunkReport(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestVolumeMgr_applyChunkReportWithVolumeOverbought(t *testing.T) {
+	mockVolumeMgr, clean := initMockVolumeMgr(t)
+	defer clean()
+
+	var args []blobnode.ChunkInfo
+	for i := 0; i < volumeCount; i++ {
+		vuid := proto.EncodeVuid(proto.EncodeVuidPrefix(proto.Vid(i), 2), 1)
+		chunk := blobnode.ChunkInfo{
+			Vuid:  vuid,
+			Total: defaultChunkSize,
+			Free:  uint64(0.6 * float64(defaultChunkSize)),
+			Used:  uint64(0.4 * float64(defaultChunkSize)),
+		}
+		args = append(args, chunk)
+	}
+
+	// with VolumeOverboughtRatio, validate volume free size after chunk report
+	// as volume total * VolumeOverboughtRatio is larger than volume used, volume free should between 0 and calculated volume free
+	mockVolumeMgr.VolumeOverboughtRatio = 0.5
+	vol := mockVolumeMgr.all.getVol(args[0].Vuid.Vid())
+	err := mockVolumeMgr.applyChunkReport(context.Background(), &clustermgr.ReportChunkArgs{ChunkInfos: args})
+	require.NoError(t, err)
+	require.Greater(t, vol.volInfoBase.Free, uint64(0))
+	dataChunkNum := uint64(mockVolumeMgr.codeMode[vol.volInfoBase.CodeMode].tactic.N)
+	require.Less(t, vol.volInfoBase.Free, args[0].Free*dataChunkNum)
+
+	// with VolumeOverboughtRatio, validate volume free size after chunk report
+	// as volume total * VolumeOverboughtRatio is less than volume used, volume free should be set into 0
+	for i := range args {
+		args[i].Used = uint64(0.5 * float64(args[i].Total))
+		args[i].Free = args[i].Total - args[i].Used
+	}
+	err = mockVolumeMgr.applyChunkReport(context.Background(), &clustermgr.ReportChunkArgs{ChunkInfos: args})
+	require.NoError(t, err)
+	require.Equal(t, uint64(0), vol.volInfoBase.Free)
+}
+
 func TestVolumeMgr_ReleaseVolumeUnit(t *testing.T) {
 	mockVolumeMgr, clean := initMockVolumeMgr(t)
 	defer clean()
diff --git a/blobstore/common/proto/const.go b/blobstore/common/proto/const.go
index 9f6b4bcf6..8f581f574 100644
--- a/blobstore/common/proto/const.go
+++ b/blobstore/common/proto/const.go
@@ -216,11 +216,13 @@ const (
 	volumeStatusMax
 )
 
-// system config key,not allow delete
+// system config key, not allow to delete
 const (
-	CodeModeConfigKey    = "code_mode"
-	VolumeReserveSizeKey = "volume_reserve_size"
-	VolumeChunkSizeKey   = "volume_chunk_size"
+	CodeModeConfigKey        = "code_mode"
+	VolumeReserveSizeKey     = "volume_reserve_size"
+	VolumeChunkSizeKey       = "volume_chunk_size"
+	VolumeOverboughtRatioKey = "volume_overbought_ratio"
+	ChunkOversoldRatioKey    = "chunk_oversold_ratio"
 )
 
 func IsSysConfigKey(key string) bool {