Hello Gaurav,
Initial I have started upgrade with SP12. At preprocessing phase while creating shadow instance, SUM tool stopped abdruptly due to space issue. I have cleaned some files in the drive and started the SUM tool again then I faced the same issue MEM file got corrupted.
So I have resetted the upgrade and started with SP11 from the scartch with single system option, now got stuck at execution phase.
Regards
Praveen