MSDO & PureDisk

Im not sure I have heard of MSDO

MSDP ( Media Server Deduplication Pool ) is a dedupe pool run directly from the media server within Netbackup itself.

PDDO ( PureDisk Deduplication Option ) is a dedupe pool that is run on a Puredisk server which is then attached into your Netbackup domain ie its external to the media server.

MSDP in 7.5 is limited to 64TB where is PDDO can extend to 196TB by combining multiple Puredisk servers together.

Unless your enviroment is really large and you require a long retention MSDP is generally fine.

Puredisk is really a dead end product now . MDSP behind the scenes is a Puredisk PDDO that has been intergrated into Netbackup.

PDDO just adds another level of complexity to your enviroment.

I hope that explains it a bit.