#Distributed Data Management

I'm playing with %Net.DB.Iris and stumbled over a mystery

set con=##class(%Net.DB.DataSource).CreateConnection(host,...)
set srv=con.CreateIris()
write srv.ClassMethodValue("%SYSTEM.Util","InstallDirectory")

Entering the above lines (in a terminal session) on my local instance yields the correct answer for:

host = "localhost"
host = the real IP of localhost (i.e. host="192.168...")
host = "10.x.y.dev" customers development system (over a VPN tunnel)

but for

host = "10.x.y.tst" (customers test system) I get an error:
 <THROW>zClassMethodValue+8^%Net.DB.Iris.

While creating namespaces, there is a provision for keeping the data, and code separately in database.
What I am looking for,

What are the benefit we can achieve by doing this?

Is there any documentation of article which might help understanding?

Thanks You!

We are finally planning to migrate some ancient Caché applications that are run on Caché 5.0.21 to a new server with Caché 2016.2.0 or so.

I wonder if we could use Shadowing between those to keep the data on the new server up to date?

We would copy the Caché backup from the old environment to the new and do a RESTORE there and then start shadowing.

I know than 5.0.21 is no more officially supported by ISC.

Consider a design where there could be three or four or more servers and there is a need to have these eventually consistent between them all (and not considering database mirroring here).  

The current Caché documentation here demonstrates this well using object synchronization between two servers, however it doesn't indicate whether more than two servers can participate to create a "mesh type" deployment.  Below is a diagram of what I'm curious to know is possible to implement with Object Synchronization.