I asked the exact same question on this forum about 6 months ago, but haven't got a single reply. 😞
Microsoft is a bit vague about it, but in their document "Windows Server High Availability with Microsoft MPIO" on www.microsoft.com/mpio they say:
"Multipath software suites available from storage IHV’s typically provide an additional value add beyond the implementation of the MSDSM as the software typically also provides auto configuration, heuristics for specific storage arrays, as well as statistical analysis, and integrated management, It’s generally recommended to use the DSM provided by the hardware storage array partner to achieve optimal performance since the storage array partner can make more advanced path decisions in their DSM specific to their array."
NetApp says something similar in their documentation on MPIO.
Microsoft DSM has a few benifits as well:
- cheaper (builtin feature of WIndows 2008)
- ALUA aware (ONTAP DSM isn't, strangely)
We decided against using Microsoft DSM. Breaking point being the recommendation of both companies to use the vendor's DSM.
Hope it helps.
Bjorn