  We present two lower bounds on sub-packetization level $\alpha$ of MSR codes
with parameters $(n, k, d=n-1, \alpha)$ where $n$ is the block length, $k$
dimension, $d$ number of helper nodes contacted during single node repair and
$\alpha$ the sub-packetization level. The first bound we present is for any MSR
code and is given by $\alpha \ge e^{\frac{(k-1)(r-1)}{2r^2}}$.
  The second bound we present is for the case of optimal-access MSR codes and
the bound is given by $\alpha \ge \min \{ r^{\frac{n-1}{r}}, r^{k-1} \}$. There
exist optimal-access MSR constructions that achieve the second
sub-packetization level bound with an equality making this bound tight.
  We also prove that for an optimal-access MSR codes to have optimal
sub-packetization level under the constraint that the indices of helper symbols
are dependant only on the failed node, it is needed that the support of the
parity check matrix is same as the support structure of several other optimal
constructions in literature.
