Since there is no formal standard for multiprotocol filesystems ( specifically how the various access controls work together ) you are best off asking about specific source -> target scenarios.

Emcopy will preserve ( as best as possible ) the MS ACL but there is no guarantee that it will be a 1:1 on the NFS permissions.  Unfortunately I have no experience with Nexsan ( what's providing the protocol on top of the san? ).  From my understanding of most of these tools you can either preserve the MS ACL or the POSIX ACL but you are likely to run into fidelity problems if you have a mix.

ok nexsan E60 -> isilon.

I can migrate data via emcopy but not sure if this is the preferred way.

castleknock,

Eric_w above's reply is correct there is no standard for how to do it, because it depends entirely on what your source/target are, and what they support, along with what your desired behavior is.  Anyway I could talk for hours perhaps days about this subject, but one of our SEs (Steve Leeper) put it in a great blog post a couple of months ago, as well as a whitepaper. 

Blog Post:

http://www.datadobi.com/blogpost/understanding-permission-types-in-multiprotocol-migrations/

WhitePaper:

http://www.datadobi.com/wp-content/uploads/2017/02/Multiprotocol-Effective-vs-Display-Permissions.pdf

Anyway, my company makes Migration Software; so call this a shameless plug if you want but there is nothing else in the industry as flexible or as fast when it comes to exactly what you're looking for here.

Reach out if you want more info than what Steve's blog post above provides:

~Chris Klosterman

Principal SE, Datadobi

chris.klosterman@datadobi.com