We are a small unit of 2 people in our Central IT group providing GIS infrastructure to our agency with about 300 users of which 60 are doing GIS as their primary jobs. We have an ArcGIS Online account for Organizations and ArcGIS Server but have been resisting spinning up a version of Portal internally.
My question is, are ArcGIS Online and Portal redundant? Since we have ArcGIS Online and ArcGIS Server is there really a need for Portal?
Wow, that's a big question. There are similarities and differences. For starters, take a look at this article:
This may give a somewhat visual presentation between the two:
Here is another presentation on it:
I suppose the way that I would approach this would be to look up some information on each of the two systems, or maybe better yet, talk to your local Esri rep to discuss what is best for your organization.
For our agency, which also has a small GIS infrastructure group, which are also part of our <10 full-time GIS), but with about 300 part-time ArcGIS users, and of course many GIS consumers, I haven't found a need to fire up an internal Portal yet. There may com a time where I would like this. I see Portal as being a need if you need to keep things 100% internal or within the firewall. But there are other options, like just using the security within ArcGIS Server, to accomplish the internal-use only that we need.
The other place I can see that it would be handy is using some of the web apps (Web App Builder) and many of the other apps and software that are becoming more reliant on AGOL/Portal to authenticate their use, whether just because it needs a (public) basemap, or it needs a named user). For better or worse, this does seem to be the way all things are heading. We do not have enough named users to allow all to access via a log in, so then we have the choice of the AGOL-public option or again, looking at internal security options. So far, we've been using the internally controllable options (thru ArcGIS Server), but that could change as we try to make more of our data/services in an available format for the public (a work in progress).
I guess another option would be is a split between the too (names users, some in Portal, some in AGOL), if for no other reason but to take advantage creating an http://opendata.arcgis.com/ site. Again, even for OpenData, I see keeping the control, and maybe the data itself local (thru .zip shapes and or GP services), while providing a public metadata and link.
Anyway, just some of my thoughts on the subject. Always good for me to see what others have done or are planning too.
If all of your organization's requirements for a web mapping system are met by ArcGIS Online, then Portal for ArcGIS is redundant, very costly (staff time) to support, maintain and update, and out of sync with ArcGIS Online capabilities (delayed).
Just to add onto what the others have posted, you may want to watch this UC tech session video,
Between 8 mins to 22:10 mins, the different Web GIS deployment patterns are discussed and near the end we review some reasons why you would choose ArcGIS Online vs. Portal for ArcGIS and vice-versa.
Hope this helps,
Some Pros for Portal:
Some Cons for Portal:
(Portal, AGS, Data Store and IIS/Web Adaptors.)
e.g. I'm waiting for 10.5 because it offers some functionality in Portal that is now available in AGOL. Supposedly, this is switching though to where new functionality will first be released with Portal?
If you do stand up Portal, highly recommend first taking Esri's fairly new course: "Deploying Portal for ArcGIS" .
There are other ways to extend your work with ArcGIS server without Portal, that is when you run in usage limitations, You can check, usually be open to implement multiple solutions, there is no one solution that fits all, portal. web app builder and others, now I suggest to go hybrid and expose your arcgis server to external libraries to be more open and more standard compliant you can try
ESRI GeoPortal Server Esri Geoportal Server | Open Source Metadata Management
terriajs TerriaJS - Geospatial catalog exploration library you can combine any data source and create your catalogs via services or manually, this viewer is probably the richest in terms of geospatial content you can view in your map