diff --git a/extern/sector-storage/piece_provider.go b/extern/sector-storage/piece_provider.go
index fd54d2166..9d7ff907b 100644
--- a/extern/sector-storage/piece_provider.go
+++ b/extern/sector-storage/piece_provider.go
@@ -57,6 +57,7 @@ func (p *pieceProvider) tryReadUnsealedPiece(ctx context.Context, sector storage
 	// the unsealed piece.
 	r, err := p.storage.Reader(ctx, sector, abi.PaddedPieceSize(offset.Padded()), size.Padded())
 	if err != nil {
+		log.Debugf("failed storage reader;sector=%+v, err:%s", sector.ID, err)
 		cancel()
 		return nil, nil, err
 	}
diff --git a/extern/sector-storage/stores/remote.go b/extern/sector-storage/stores/remote.go
index 7400c6ee0..741928fdf 100644
--- a/extern/sector-storage/stores/remote.go
+++ b/extern/sector-storage/stores/remote.go
@@ -510,6 +510,7 @@ func (r *Remote) Reader(ctx context.Context, s storage.SectorRef, offset, size a
 		log.Infof("Read local %s (+%d,%d)", path, offset, size)
 		ssize, err := s.ProofType.SectorSize()
 		if err != nil {
+			log.Debugf("failed to get sectorsize: %s", err)
 			return nil, err
 		}
 
@@ -530,6 +531,7 @@ func (r *Remote) Reader(ctx context.Context, s storage.SectorRef, offset, size a
 			if err := r.pfHandler.Close(pf); err != nil {
 				return nil, xerrors.Errorf("close partial file: %w", err)
 			}
+			log.Debugf("miner has unsealed file but not unseal piece, %s (+%d,%d)", path, offset, size)
 			return nil, nil
 		}