They have small interface buffers. Often SAN servers will often have so much egress traffic packets are lost due to lack of buffers. That said, buffer (Qos) tuning can sometime (even much) mitigate the issue. (BTW, older 3560/3750 have similar issue, although they have a bit more buffer memory).
As Reza suggests, Nexus series would be a better, if not best, choice. A more enterprise/carrier grade switch often will be much better too, i.e. the Catalyst 4K or 6k families.
