diff --git a/weed/command/server.go b/weed/command/server.go
index 78b52ea4b..f92feb11d 100644
--- a/weed/command/server.go
+++ b/weed/command/server.go
@@ -132,7 +132,7 @@ func init() {
 	serverOptions.v.idxFolder = cmdServer.Flag.String("volume.dir.idx", "", "directory to store .idx files")
 	serverOptions.v.inflightUploadDataTimeout = cmdServer.Flag.Duration("volume.inflightUploadDataTimeout", 60*time.Second, "inflight upload data wait timeout of volume servers")
 	serverOptions.v.hasSlowRead = cmdServer.Flag.Bool("volume.hasSlowRead", false, "<experimental> if true, this prevents slow reads from blocking other requests, but large file read P99 latency will increase.")
-	serverOptions.v.readBufferSize = cmdServer.Flag.Int("volume.readBufferSize", 1024 * 1024, "<experimental> larger values can optimize query performance but will increase some memory usage,Use with hasSlowRead normally")
+	serverOptions.v.readBufferSizeMB = cmdServer.Flag.Int("volume.readBufferSizeMB", 4, "<experimental> larger values can optimize query performance but will increase some memory usage,Use with hasSlowRead normally")
 
 	s3Options.port = cmdServer.Flag.Int("s3.port", 8333, "s3 server http listen port")
 	s3Options.portGrpc = cmdServer.Flag.Int("s3.port.grpc", 0, "s3 server grpc listen port")
diff --git a/weed/command/volume.go b/weed/command/volume.go
index 5b62a4844..24945d0e3 100644
--- a/weed/command/volume.go
+++ b/weed/command/volume.go
@@ -67,7 +67,7 @@ type VolumeServerOptions struct {
 	// pulseSeconds          *int
 	inflightUploadDataTimeout *time.Duration
 	hasSlowRead               *bool
-	readBufferSize            *int
+	readBufferSizeMB          *int
 }
 
 func init() {
@@ -99,7 +99,7 @@ func init() {
 	v.idxFolder = cmdVolume.Flag.String("dir.idx", "", "directory to store .idx files")
 	v.inflightUploadDataTimeout = cmdVolume.Flag.Duration("inflightUploadDataTimeout", 60*time.Second, "inflight upload data wait timeout of volume servers")
 	v.hasSlowRead = cmdVolume.Flag.Bool("hasSlowRead", false, "<experimental> if true, this prevents slow reads from blocking other requests, but large file read P99 latency will increase.")
-	v.readBufferSize = cmdVolume.Flag.Int("readBufferSize", 1024 * 1024, "<experimental> larger values can optimize query performance but will increase some memory usage,Use with hasSlowRead normally.")
+	v.readBufferSizeMB = cmdVolume.Flag.Int("readBufferSizeMB", 4, "<experimental> larger values can optimize query performance but will increase some memory usage,Use with hasSlowRead normally.")
 }
 
 var cmdVolume = &Command{
@@ -248,7 +248,7 @@ func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, v
 		int64(*v.concurrentDownloadLimitMB)*1024*1024,
 		*v.inflightUploadDataTimeout,
 		*v.hasSlowRead,
-		*v.readBufferSize,
+		*v.readBufferSizeMB,
 	)
 	// starting grpc server
 	grpcS := v.startGrpcService(volumeServer)
diff --git a/weed/server/volume_server.go b/weed/server/volume_server.go
index 07bb0b9ee..8e20b0846 100644
--- a/weed/server/volume_server.go
+++ b/weed/server/volume_server.go
@@ -29,7 +29,7 @@ type VolumeServer struct {
 	inFlightDownloadDataLimitCond *sync.Cond
 	inflightUploadDataTimeout     time.Duration
 	hasSlowRead                   bool
-	readBufferSize                int
+	readBufferSizeMB              int
 
 	SeedMasterNodes []pb.ServerAddress
 	currentMaster   pb.ServerAddress
@@ -67,7 +67,7 @@ func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 	concurrentDownloadLimit int64,
 	inflightUploadDataTimeout time.Duration,
 	hasSlowRead bool,
-	readBufferSize int,
+	readBufferSizeMB int,
 ) *VolumeServer {
 
 	v := util.GetViper()
@@ -98,7 +98,7 @@ func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 		concurrentDownloadLimit:       concurrentDownloadLimit,
 		inflightUploadDataTimeout:     inflightUploadDataTimeout,
 		hasSlowRead:                   hasSlowRead,
-		readBufferSize:                readBufferSize,
+		readBufferSizeMB:              readBufferSizeMB,
 	}
 	vs.SeedMasterNodes = masterNodes
 
diff --git a/weed/server/volume_server_handlers_read.go b/weed/server/volume_server_handlers_read.go
index facdf2556..8ad526d59 100644
--- a/weed/server/volume_server_handlers_read.go
+++ b/weed/server/volume_server_handlers_read.go
@@ -118,7 +118,7 @@ func (vs *VolumeServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 	readOption := &storage.ReadOption{
 		ReadDeleted:    r.FormValue("readDeleted") == "true",
 		HasSlowRead:    vs.hasSlowRead,
-		ReadBufferSize: vs.readBufferSize,
+		ReadBufferSize: vs.readBufferSizeMB * 1024 * 1024,
 	}
 
 	var count int