Best practices for deploying a large application to a new environment for the first time?

In the past few years they've made some quality-of-life changes to the way deployments are handled from the user-facing perspective, to make it a bit less of a hassle when we're talking about potential timeouts for large applications.  In the past they used to try and synchronously run the entire deployment then show a success screen, but any deployment larger than "moderately small" (or thereabouts) seemed to hit the timeout limit and you'd be stuck waiting for the error, then crossing your fingers that it worked fine on the remote side.  Now, instead, it just takes the deployER to a "deployment in progress, press the Close button then go check the target environment..." form, which you can get out of right away.

For your approach splitting up the packages - that's about what I'd recommend (DB objects, followed by other application pieces).  I'm not sure how necessary it is to split out the groups, though it also shouldn't hurt and I guess it's clean from a dependency standpoint, since groups can't really depend on other object types (unless i'm blanking on something).

Maybe it's too late but if you have an empty TEST or UAT environment, it might be the perfect chance to test out your approach there, before trying it for the first time for your PROD deployment.  But I understand that circumstances don't always really allow this.

I do not split up apps. This was a best practice from >10 years ago and not necessary anymore. Many people still insist on doing it and when I ask why, I get back: "We've always done it this way. Someone once said that's how it should be."

I try to build my best practices on facts, not on legends.

And yes, I know, there are certain situations in which splitting up CAN help.

IIRC it helps to stratify and specify where something went wrong if something goes wrong.  Appian handles this better now but I don't pretend it handles it perfectly yet.

I don't split up objects by object type but 3K objects is quite big IMO. My preference is for applications in the 1000-1500 object range.

If it gets bigger than that, I would consider trying to split them up into 2 or 3 independant applications which communicate via APIs.

Thanks Mike, we were able to deploy the DB and group application folders. I'm trying to deploy the main application folder now, but it seems to go to "Inspect Deployment" and then we get the following screen:

Any ideas on how to resolve this? I'm assuming it's timing out.

How many objects does this comprise?

Also do you see any more information in the tomcat-stdout log?

3299, it seems to get to the review screen eventually after the error message and then we're able to inspect the package on the destination environment. The next issue we're facing is that the inspection on the destination environment reports that there are missing record types, but we've triple checked that the record types are added. I've checked the forums and it seems that this is a known issue. Any ideas on how to get around it? I was going to try and deploy them separately but there's too many dependencies.

If you've ensured the record types are actually in the app package, you could always try deploying anyway and see what happens. 

The only other thing I can think of suggesting would be to go through with your alternative idea - create a separate app and/or package with all (or maybe just cherrypick some of the bigger) record type(s), add all prcedents (and suffer through the multiple levels of re-checking etc), and deploy just that.

Or if you don't want to try any of the messier approaches, open a case with Appian Support and get their official feedback on why you're getting errors when trying to do it the "right" way.

Cheers Mike, I might just try deploying it anyway then and seeing how it goes. As always, thank you so much for all your help!