diff --git a/weed/shell/command_volume_check_disk.go b/weed/shell/command_volume_check_disk.go
index d7b015979..c8f28bf04 100644
--- a/weed/shell/command_volume_check_disk.go
+++ b/weed/shell/command_volume_check_disk.go
@@ -10,6 +10,8 @@ import (
 	"math"
 	"math/rand/v2"
 	"net/http"
+	"strings"
+	"sync"
 	"time"
 
 	"slices"
@@ -32,6 +34,7 @@ type commandVolumeCheckDisk struct{}
 type volumeCheckDisk struct {
 	commandEnv *CommandEnv
 	writer     io.Writer
+	writerMu   sync.Mutex
 	now        time.Time
 
 	slowMode           bool
@@ -146,14 +149,14 @@ func (c *commandVolumeCheckDisk) Do(args []string, commandEnv *CommandEnv, write
 
 // checkWritableVolumes fixes volume replicas which are not read-only.
 func (vcd *volumeCheckDisk) checkWritableVolumes(volumeReplicas map[uint32][]*VolumeReplica) error {
-	vcd.write("Pass #1 (writable volumes)\n")
+	vcd.write("Pass #1 (writable volumes)")
 
 	for _, replicas := range volumeReplicas {
 		// filter readonly replica
 		var writableReplicas []*VolumeReplica
 		for _, replica := range replicas {
 			if replica.info.ReadOnly {
-				vcd.write("skipping readonly volume %d on %s\n", replica.info.Id, replica.location.dataNode.Id)
+				vcd.write("skipping readonly volume %d on %s", replica.info.Id, replica.location.dataNode.Id)
 			} else {
 				writableReplicas = append(writableReplicas, replica)
 			}
@@ -166,7 +169,7 @@ func (vcd *volumeCheckDisk) checkWritableVolumes(volumeReplicas map[uint32][]*Vo
 			a, b := writableReplicas[0], writableReplicas[1]
 			shouldSkip, err := vcd.shouldSkipVolume(a, b)
 			if err != nil {
-				vcd.write("error checking if volume %d should be skipped: %v\n", a.info.Id, err)
+				vcd.write("error checking if volume %d should be skipped: %v", a.info.Id, err)
 				// Continue with sync despite error to be safe
 			} else if shouldSkip {
 				// always choose the larger volume to be the source
@@ -174,7 +177,7 @@ func (vcd *volumeCheckDisk) checkWritableVolumes(volumeReplicas map[uint32][]*Vo
 				continue
 			}
 			if err := vcd.syncTwoReplicas(a, b, true); err != nil {
-				vcd.write("sync volume %d on %s and %s: %v\n", a.info.Id, a.location.dataNode.Id, b.location.dataNode.Id, err)
+				vcd.write("sync volume %d on %s and %s: %v", a.info.Id, a.location.dataNode.Id, b.location.dataNode.Id, err)
 			}
 			// always choose the larger volume to be the source
 			if a.info.FileCount > b.info.FileCount {
@@ -204,7 +207,7 @@ func (vcd *volumeCheckDisk) makeVolumeWritable(vid uint32, vr *VolumeReplica) er
 		return err
 	}
 
-	vcd.write("volume %d on %s is now writable\n", vid, vr.location.dataNode.Id)
+	vcd.write("volume %d on %s is now writable", vid, vr.location.dataNode.Id)
 	return nil
 }
 
@@ -224,7 +227,7 @@ func (vcd *volumeCheckDisk) makeVolumeReadonly(vid uint32, vr *VolumeReplica) er
 		return err
 	}
 
-	vcd.write("volume %d on %s is now read-only\n", vid, vr.location.dataNode.Id)
+	vcd.write("volume %d on %s is now read-only", vid, vr.location.dataNode.Id)
 	return nil
 }
 
@@ -232,7 +235,7 @@ func (vcd *volumeCheckDisk) checkReadOnlyVolumes(volumeReplicas map[uint32][]*Vo
 	if !vcd.fixReadOnly {
 		return nil
 	}
-	vcd.write("Pass #2 (read-only volumes)\n")
+	vcd.write("Pass #2 (read-only volumes)")
 
 	for vid, replicas := range volumeReplicas {
 		roReplicas := []*VolumeReplica{}
@@ -246,11 +249,11 @@ func (vcd *volumeCheckDisk) checkReadOnlyVolumes(volumeReplicas map[uint32][]*Vo
 			}
 		}
 		if len(roReplicas) == 0 {
-			vcd.write("no read-only replicas for volume %d\n", vid)
+			vcd.write("no read-only replicas for volume %d", vid)
 			continue
 		}
 		if len(rwReplicas) == 0 {
-			vcd.write("got %d read-only replicas for volume %d and no writable replicas to fix from\n", len(roReplicas), vid)
+			vcd.write("got %d read-only replicas for volume %d and no writable replicas to fix from", len(roReplicas), vid)
 			continue
 		}
 
@@ -261,7 +264,7 @@ func (vcd *volumeCheckDisk) checkReadOnlyVolumes(volumeReplicas map[uint32][]*Vo
 
 			skip, err := vcd.shouldSkipVolume(r, source)
 			if err != nil {
-				vcd.write("error checking if volume %d should be skipped: %v\n", r.info.Id, err)
+				vcd.write("error checking if volume %d should be skipped: %v", r.info.Id, err)
 				continue
 			}
 			if skip {
@@ -276,13 +279,13 @@ func (vcd *volumeCheckDisk) checkReadOnlyVolumes(volumeReplicas map[uint32][]*Vo
 			// ...fix it...
 			// TODO: test whether syncTwoReplicas() is enough to prune garbage entries on broken volumes.
 			if err := vcd.syncTwoReplicas(source, r, false); err != nil {
-				vcd.write("sync read-only volume %d on %s from %s: %v\n", vid, r.location.dataNode.Id, source.location.dataNode.Id, err)
+				vcd.write("sync read-only volume %d on %s from %s: %v", vid, r.location.dataNode.Id, source.location.dataNode.Id, err)
 
 				// ...or revert it back to read-only, if something went wrong.
 				if roErr := vcd.makeVolumeReadonly(vid, r); roErr != nil {
 					return fmt.Errorf("failed to make volume %d on %s readonly after: %v: %v", vid, r.location.dataNode.Id, err, roErr)
 				}
-				vcd.write("volume %d on %s is now read-only\n", vid, r.location.dataNode.Id)
+				vcd.write("volume %d on %s is now read-only", vid, r.location.dataNode.Id)
 
 				return err
 			}
@@ -297,12 +300,15 @@ func (vcd *volumeCheckDisk) grpcDialOption() grpc.DialOption {
 }
 
 func (vcd *volumeCheckDisk) write(format string, a ...any) {
-	fmt.Fprintf(vcd.writer, format, a...)
+	vcd.writerMu.Lock()
+	defer vcd.writerMu.Unlock()
+	fmt.Fprintf(vcd.writer, strings.TrimRight(format, "\r\n "), a...)
+	fmt.Fprint(vcd.writer, "\n")
 }
 
 func (vcd *volumeCheckDisk) writeVerbose(format string, a ...any) {
 	if vcd.verbose {
-		fmt.Fprintf(vcd.writer, format, a...)
+		vcd.write(format, a...)
 	}
 }
 
@@ -388,7 +394,7 @@ func (vcd *volumeCheckDisk) shouldSkipVolume(a, b *VolumeReplica) (bool, error)
 			if doSyncDeletedCount && !eqDeletedFileCount {
 				return false, nil
 			}
-			vcd.writeVerbose("skipping active volumes %d with the same file counts on %s and %s\n",
+			vcd.writeVerbose("skipping active volumes %d with the same file counts on %s and %s",
 				a.info.Id, a.location.dataNode.Id, b.location.dataNode.Id)
 		} else {
 			return false, nil
@@ -406,7 +412,7 @@ func (vcd *volumeCheckDisk) syncTwoReplicas(source, target *VolumeReplica, bidi
 
 	for (sourceHasChanges || targetHasChanges) && iteration < maxIterations {
 		iteration++
-		vcd.writeVerbose("sync iteration %d/%d for volume %d\n", iteration, maxIterations, source.info.Id)
+		vcd.writeVerbose("sync iteration %d/%d for volume %d", iteration, maxIterations, source.info.Id)
 
 		prevSourceHasChanges, prevTargetHasChanges := sourceHasChanges, targetHasChanges
 		if sourceHasChanges, targetHasChanges, err = vcd.checkBoth(source, target, bidi); err != nil {
@@ -415,14 +421,14 @@ func (vcd *volumeCheckDisk) syncTwoReplicas(source, target *VolumeReplica, bidi
 
 		// Detect if we're stuck in a loop with no progress
 		if iteration > 1 && prevSourceHasChanges == sourceHasChanges && prevTargetHasChanges == targetHasChanges && (sourceHasChanges || targetHasChanges) {
-			vcd.write("volume %d sync is not making progress between %s and %s after iteration %d, stopping to prevent infinite loop\n",
+			vcd.write("volume %d sync is not making progress between %s and %s after iteration %d, stopping to prevent infinite loop",
 				source.info.Id, source.location.dataNode.Id, target.location.dataNode.Id, iteration)
 			return fmt.Errorf("sync not making progress after %d iterations", iteration)
 		}
 	}
 
 	if iteration >= maxIterations && (sourceHasChanges || targetHasChanges) {
-		vcd.write("volume %d sync reached maximum iterations (%d) between %s and %s, may need manual intervention\n",
+		vcd.write("volume %d sync reached maximum iterations (%d) between %s and %s, may need manual intervention",
 			source.info.Id, maxIterations, source.location.dataNode.Id, target.location.dataNode.Id)
 		return fmt.Errorf("reached maximum sync iterations (%d)", maxIterations)
 	}
@@ -512,7 +518,7 @@ func (vcd *volumeCheckDisk) doVolumeCheckDisk(minuend, subtrahend *needle_map.Me
 		return nil
 	})
 
-	vcd.write("volume %d %s has %d entries, %s missed %d and partially deleted %d entries\n",
+	vcd.write("volume %d %s has %d entries, %s missed %d and partially deleted %d entries",
 		source.info.Id, source.location.dataNode.Id, counter, target.location.dataNode.Id, len(missingNeedles), len(partiallyDeletedNeedles))
 
 	if counter == 0 || (len(missingNeedles) == 0 && len(partiallyDeletedNeedles) == 0) {
@@ -536,7 +542,7 @@ func (vcd *volumeCheckDisk) doVolumeCheckDisk(minuend, subtrahend *needle_map.Me
 			continue
 		}
 
-		vcd.writeVerbose("read %s %s => %s\n", needleValue.Key.FileId(source.info.Id), source.location.dataNode.Id, target.location.dataNode.Id)
+		vcd.writeVerbose("read %s %s => %s", needleValue.Key.FileId(source.info.Id), source.location.dataNode.Id, target.location.dataNode.Id)
 		hasChanges = true
 
 		if err = vcd.writeNeedleBlobToTarget(pb.NewServerAddressFromDataNode(target.location.dataNode), source.info.Id, needleValue, needleBlob); err != nil {
@@ -549,7 +555,7 @@ func (vcd *volumeCheckDisk) doVolumeCheckDisk(minuend, subtrahend *needle_map.Me
 		var fidList []string
 		for _, needleValue := range partiallyDeletedNeedles {
 			fidList = append(fidList, needleValue.Key.FileId(source.info.Id))
-			vcd.writeVerbose("delete %s %s => %s\n", needleValue.Key.FileId(source.info.Id), source.location.dataNode.Id, target.location.dataNode.Id)
+			vcd.writeVerbose("delete %s %s => %s", needleValue.Key.FileId(source.info.Id), source.location.dataNode.Id, target.location.dataNode.Id)
 		}
 		deleteResults := operation.DeleteFileIdsAtOneVolumeServer(
 			pb.NewServerAddressFromDataNode(target.location.dataNode),
@@ -604,7 +610,7 @@ func (vcd *volumeCheckDisk) readIndexDatabase(db *needle_map.MemDb, collection s
 		return err
 	}
 
-	vcd.writeVerbose("load collection %s volume %d index size %d from %s ...\n", collection, volumeId, buf.Len(), volumeServer)
+	vcd.writeVerbose("load collection %s volume %d index size %d from %s ...", collection, volumeId, buf.Len(), volumeServer)
 	return db.LoadFilterFromReaderAt(bytes.NewReader(buf.Bytes()), true, false)
 }
 
diff --git a/weed/shell/command_volume_check_disk_test.go b/weed/shell/command_volume_check_disk_test.go
index eee9103a8..ec958fbc4 100644
--- a/weed/shell/command_volume_check_disk_test.go
+++ b/weed/shell/command_volume_check_disk_test.go
@@ -278,14 +278,14 @@ func TestVolumeCheckDiskHelperMethods(t *testing.T) {
 	}
 
 	// Test write method
-	vcd.write("test %s\n", "message")
+	vcd.write("test %s", "message")
 	if buf.String() != "test message\n" {
 		t.Errorf("write() output = %q, want %q", buf.String(), "test message\n")
 	}
 
 	// Test writeVerbose with verbose=true
 	buf.Reset()
-	vcd.writeVerbose("verbose %d\n", 123)
+	vcd.writeVerbose("verbose %d", 123)
 	if buf.String() != "verbose 123\n" {
 		t.Errorf("writeVerbose() with verbose=true output = %q, want %q", buf.String(), "verbose 123\n")
 	}
@@ -293,7 +293,7 @@ func TestVolumeCheckDiskHelperMethods(t *testing.T) {
 	// Test writeVerbose with verbose=false
 	buf.Reset()
 	vcd.verbose = false
-	vcd.writeVerbose("should not appear\n")
+	vcd.writeVerbose("should not appear")
 	if buf.String() != "" {
 		t.Errorf("writeVerbose() with verbose=false output = %q, want empty", buf.String())
 	}