How to work with large (linked) files

Very interesting discussion in RFO taking place. The thread started with a question about best practises for sharing models with consultants. For me, it became very interesting when the discussion wondered around post #16 to purging models before linking them in. A post from a Curtain Wall detailer (important detail, no pun intended), let's call him Dave, set the debate on fire: his current project had a few links in them, six to be exact. Largest: 517mb, and a few 300+ mb files.
Quick calculation adds up to a staggering 1.5GB of linked Revit models (no pointclouds to my knowledge).

Naturally his performance was lagging so he had been looking into purging the models. I, amongst others, don't think that's a very good idea. Why not?

1. Revit works with a database. That means that all families you load are stored inside that database once and then referenced from the model. Different types get separate additional info or something. Don't quite know how it works, what I DO know is that you can put window A one time or 100 times in your project, it's not going to make a difference in size. It does make a difference in regeneration time off course. Same goes for views: the settings (what kind of view, where is it at, what are we showing) are stored somewhere inside the database but only utilized when called upon.

BUT: logically this means that families inside your project that are not being used do NOT affect the responsetime when working on the project. They're in the database but they are not referenced. So they are dead weight. Same goes for views, sheets and all other stuff floating around in the link: as long as it's not referenced, it's of no importance to the model's performance.

2. Dave tried purging all his links. Which cost him more then a day from the looks of it. I mean, if it costs you 3 hours to LOAD the purge screen, how long will it have taken to actually delete all that stuff. And that times 6! What did it get him?
- The architects model went down in size from 517 to 397mb
- A structural file went down from 381mb to 325mb.
With that he reported a significant increase of responsiveness (if that's even a word) of the model. In plain english: it worked better, more smoothly, with lots less regeneration time and so on.
Which, according to my statement above, shouldn't be possible... So who is right here?

I think that this is a big numbers thing. With every action you tike while modelling, Revit needs to search it's database for the corresponding elements. That takes time. If you cut down a 1.5GB model to 1GB, this is going to affect search time. Simple as that.
HOWEVER: this effect is limited. You can purge only so much and let's face it: if modelled and delivered to you right, you shouldn't be able to purge out 25% of the filesize anyway.

3. Dave decided to skip weekly updates of the links because that would mean going through this entire process again. Which in my very humble opinion is a logical but very dangerous complication.


So what IS a working solution?
Let's assume the model has worksets in it. If there weren't any, my advice wouldn't be much different. Just skip step one:

1. Open the link. If needed, purge all worksets. To do so, see image 1 to 4.
2. Re-enable worksets, move all items to the default "Workset1" when prompted.
3. Add 1 workset. Call it "Load" or something, see image 5.
4. Move all items you wish to work on/with to this workset. To do this, select them in your model and go to the Properties window. Change the Workset from Workset1 to Load, see image6.
5. Open the Workset Dialogue Box and set Workset1 to be not-loaded, just to check whether you got all the elements you need, see image7.
6. Link the file into your own project and presto...

Image1: Select file you want to Link and click Detach from central

Image2: Disregard the warning (if prompted)

Image3: Select all worksets to load

Image4: The money shot, delete all worksets present

Image5: add your own worksets

Image6: Add desired elements to your workset

Image7: check if all is well

WAIT A SEC...!!! (got ya)

Still seeing the entire model? That might be correct. When linking a model you need to specify the worksets you want to load. When selecting the link you need to set the options for "Open" to "Specify", see image 8. Then in the next window select Workset1 and hit Close, see image9.

Image8: Selecting the option to specify Worksets

Image9:  Specifying worksets to load

I did this with an 80mb file.
The full link took about 55sec to load  in the first place and after that 10-15sec on actions like
- selecting the link
- creating a section view
- switching views.

When testing the workflow I took one elevation and placed the Curtain Walls in a workset. Needless to say that the reload, selecting, sectioning and all that stuff was pretty much instantly.

Now as you might have noticed I used a project which already had worksets in them. So why not use those? Well, because they didn't meet my needs. By discarding the original worksets and creating my own I could handpick all items I needed to work on for this elevation. In this case, worksets were made for ALL elevations, structure, interior, and that sort of thing. I figured that if I was Dave, I would be working on one elevation at a time. So by handselecting the elements needed for a specific (set of) tasks I could minimize the dead weight in my project file even more.

Another great thing about this workflow:
I could also use a naming strategy and create predefined worksets for all elevations separately. Now, when reloading the link in my project I can very quickly switch between building parts I need to see and/or work with by Closing and Opening Worksets through the Manage Links window.

In conclusion:
You will need to do this with every new set of consultant files you get. But in my opinion it will go way faster then purging. AND it gives you more flexibility and better results.

Happy Reviting!
Mark Twain