shard id starts from zero

weed/storage/erasure_coding/ec_encoder.go

@@ -94,7 +94,7 @@ func encodeData(file *os.File, enc reedsolomon.Encoder, startOffset, blockSize i
 
 func openEcFiles(baseFileName string, forRead bool) (files []*os.File, err error) {
 	for i := 0; i < DataShardsCount+ParityShardsCount; i++ {
-		fname := baseFileName + ToExt(i+1)
+		fname := baseFileName + ToExt(i)
 		openOption := os.O_TRUNC | os.O_CREATE | os.O_WRONLY
 		if forRead {
 			openOption = os.O_RDONLY

weed/storage/erasure_coding/ec_volume_info.go

@@ -1,6 +1,8 @@
 package erasure_coding
 
 import (
+	"fmt"
+
 	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
 	"github.com/chrislusf/seaweedfs/weed/storage/needle"
 )
@@ -61,3 +63,7 @@ func (ecInfo *EcVolumeInfo) ToVolumeEcShardInformationMessage() (ret []*master_p
 	}
 	return
 }
+
+func (ecInfo *EcVolumeInfo) String() string {
+	return fmt.Sprintf("id:%d shard:%v collection:%v", ecInfo.VolumeId, ecInfo.ShardIds(), ecInfo.Collection)
+}