func (ds *DiskStorage) blobDirectory(partition string, b *blobref.BlobRef) string {
d := b.Digest()
if len(d) < 6 {
d = d + "______"
}
return filepath.Join(ds.PartitionRoot(partition), b.HashName(), d[0:3], d[3:6])
}
func blobFileBaseName(b *blobref.BlobRef) string {
return fmt.Sprintf("%s-%s.dat", b.HashName(), b.Digest())
}