diff --git a/weed/mount/page_writer/upload_pipeline.go b/weed/mount/page_writer/upload_pipeline.go
index f326445a3..e1aa43fe2 100644
--- a/weed/mount/page_writer/upload_pipeline.go
+++ b/weed/mount/page_writer/upload_pipeline.go
@@ -94,7 +94,8 @@ func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsN
 			up.moveToSealed(up.writableChunks[candidateChunkIndex], candidateChunkIndex)
 			// fmt.Printf("flush chunk %d with %d bytes written\n", logicChunkIndex, oldestTs)
 		}
-		if len(up.writableChunks) < up.writableChunkLimit &&
+		if isSequential &&
+			len(up.writableChunks) < up.writableChunkLimit &&
 			atomic.LoadInt64(&memChunkCounter) < 4*int64(up.writableChunkLimit) {
 			pageChunk = NewMemChunk(logicChunkIndex, up.ChunkSize)
 		} else {