Vector bundles on elliptic curves over a discrete valuation ring

Here we study vector bundles on elliptic curves over a DVR. In particular, we classify the vector bundles whose restriction to the special fiber is stable. For singular genus one curves over a DVR, we consider the same problem for flat sheaves whose restriction to the special fiber is torsion free and obtained taking iterated extensions of a non-locally free sheaf with rank one and degree 0.