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Hard Disk when use C4R

Message 1 of 33
16395 Views, 32 Replies

Hard Disk when use C4R

Hi all,


When using C4R the minimum hard disk space as much

At present our company has many computers are using the SSD 128.


Thanks for support.

Message 2 of 33
in reply to: Anonymous

I would say 500gb is min for your C: you may get away with 250gb if you have another hard drive for storage. The way Revit is not backward compatible you need at leas 3 version of revit on your pc & with all your other software you will soon fill a 128gb

Message 3 of 33
in reply to: Anonymous

Hi Sonor,


I can see how that might be an issue on a 128 Gb drive, preferable you should have a 400-500 Gb drive at least depending on how much software you have installed, particularly if you are working with a lot of projects/models. There is a lot of data saved locally to improve performance in C4R.


If you have a  2nd drive in the system as well for data, there is a "workaround": There is a way that you can re-direct some of the the data that Revit and C4R is using (journals and collaboration cache) to your 2nd drive by using Symbolic Links, it's a bit 'involved' but I will try to explain it a good as I can.  


Make sure you change the paths and directory name below to the correct names on your system (I'm using 2017 as an example)

I also suggest that you do it on a test system before you change a production system.



1. Create a new 'root' folder on your 2nd drive where you want to store this data, for example  D:\RevitUserAppdata

If you have more that one Windows login on this system, you will need to create a separate directory for each user: for example  D:\RevitUserAppdata\[User Profile] and use this directory in the example below.


2. Make sure Revit is not running

3. Kill RevitAccelerator.exe with Task Manager


4. In Explorer, navigate to C:\Users\[User Profile]\AppData\Local\Autodesk\Revit


5. Move the two folders  'Autodesk Revit 2017" and "ParCache" to the new directory on the D-drive


6. Open a command prompt with Admin privileges (e.g Right click on it in the start menu and select "Run as administrator"


7. Change directory to the User profile directory above:

cd C:\Users\[User Profile]\AppData\Local\Autodesk\Revit


8. Run the following commands: (Note: don't miss the '/D', if you do, it will create a file link instead of a directory link)


mklink /D "Autodesk Revit 2017" "D:\RevitUserAppdata\Autodesk Revit 2017"

Should respond with : symbolic link created for Autodesk Revit 2017 <<===>> D:\RevitUserAppdata\Autodesk Revit 2017


mklink /D PacCache D:\RevitUserAppdata\PacCache

Should respond with : symbolic link created for PacCache <<===>> D:\RevitUserAppdata\PacCache


9. Start RevitAccelerator again

10. Start Revit. Revit should now access/save all the files from the new location on the d-drive. 




If you need to restore the default behavior in Revit:

1. Make sure Revit and RevitAccelerator is not running

2. Delete the two symbolic links in C:\Users\[User Profile]\AppData\Local\Autodesk\Revit

3. Move the two folders back from the D-drive



Some notes and disclaimers:

- This is not 'official' supported and not fully tested, there might be areas/functions in Revit where this is not working....

- Autodesk (or me) is not responsible for any loss of data or crashes due to this. It shouldn't happen but just had to put it here just in case 😉

I suggest that you do it on a test system before you change a production system


- The changes are only for one WIndows user - if there is more than one user on the system, you will have to make the changes for them as well. You will also need to make separate 'root'-folders on the 2nd drive for each user, otherwise you will most likely corrupt your models


- Depending on the performance of the 2nd drive (compared to the SSD), this might affect performance in Revit.



More on Symbolic Links:



Lars-Ake Johansson
Sr. SQA Engineer
Message 4 of 33
in reply to: lars-ake.johansson

How has this worked?


This is the one aspect of C4R that im trying to change.


Rather than it be a local copy on my C:Drive, i want to have it stored on an a DATA drive, which can then be backed up onto a server daily.


Two reasons.


1. SSD arent cheap and i try to keep them as clean as possible. I do have a 512GB SSD, but my Senior and Junior only have 256GB.

2. if my C Drive dies i want to be able to ensure the Data in C4R isnt lost (i know its Cloud Hosted)


All my systems are set up the same way


1. SSD (Approx 256GB)

1. Data Storage (2TB SSHD Split into 4 Partitions. 1 x 250GB for Box, 1 x 250GB for Onedrive, 1 x 1500GB for A360 or Drafting)


so im super interested to see if this is working for everyone.

Message 5 of 33
in reply to: Anonymous

@scott any luck with the workaround above? We are having the exact same issue.


Small SSD's, large HDD data drive. Unable to repath any of the C4R files.


This is a concerning issue that there is no repathing solution in Revit.


Can anyone report that they have managed to apply this workaround??? Our project has only just begun & we are already having issues on a number of stations.

'A person without much talent or ability is considered special by those with no talent or ability at all'
Message 6 of 33
in reply to: DTND

nope. its abit ackward to be honest.


the only work around i have found is the one that stated earlier, but when you start getting to that level its beyond what im comfortable to do at work incase it goes wrong.


i may play around with it at home to test it, either way, i dont think it would be too hard for Autodesk to introduce something to allow us to direct it to a specific location ..

Message 7 of 33
in reply to: Anonymous

yeah I hear ya.. any one from ADSK care to comment??


We will log a idea request.. please vote up!!!


'A person without much talent or ability is considered special by those with no talent or ability at all'
Message 8 of 33
in reply to: DTND

Using symbolic links is the best way t re-direct the Collabortion Cache data for C4R.  We are not aware of any negative consequences for teams that have implemented it.  Only reports of success.



Kyle Bernhardt
Building Design Strategy
Autodesk, Inc.

Message 9 of 33

Works perfectly fine, very staight forward steps too. But how to restart Revit Accelerator process again ?



Message 10 of 33
in reply to: KyleB_Autodesk

The ideal solution would be for Autodesk to include a way to path these to less expensive storage. Going in and repathing every single user is not realistic in an enterprise environment. 

Message 11 of 33

you can restart the Revit Accelerator by launching it from C:\Program Files\Autodesk\Personal Accelerator for Revit.


If it does not launch then most likely you have an error in the path statements you created in step 8.


I had this happen because I forgot to include "[User Profile]" in the mklink strings...   Step 1 tells you to create this in the  D:\RevitUserAppdata folder but then this is not included in step 8.  Hence in step 8 the strings should read:

mklink /D "Autodesk Revit 2017" "D:\RevitUserAppdata\[User Profile]\Autodesk Revit 2017"

mklink /D PacCache D:\RevitUserAppdata\[User Profile]\PacCache


Possibly after step 8, another step should be added before step 9.   that step would be to go to  C:\Users\[User Profile]\AppData\Local\Autodesk\Revit and double-click all the links you created in step 8.  that way you would be testing if the links work correctly before trying to re-launch Revit Accelerator.



Message 12 of 33

Hi Lars-Ake Johansson,


Thanks. That information was very helpful for previous versions of Revit, we cannot seem to get that to work with 2019. Has something changed?


Thank you,



Message 13 of 33

I am using it in 2019.  It is working just fine.  My cache files are now located on my E drive. 


Check your links after you make them.  Are they correct?  See my post in message 11.


I did notice that Revit Accelerator is no longer running or possibly needed in 2019.  Since all my projects upgraded to 2019 I uninstalled my older versions of Revit (ver 2017 and 2018).  I believe that also uninstalled Revit Accelerator but I have not found any documentation to prove this yet.


I was also able to use the same concept and move my Autodesk folder in ProgramData over to E too.  This gave me more room on my small SSD C drive to then increase the size of my Page File.  That has really helped to speed up my system.  Reboot to safe mode to move ProgramData.  There is more about these concepts here:



Message 14 of 33
in reply to: bill_hashman

Hi Bill:

re: "...Revit Accelerator is no longer...possibly needed in 2019"

You should definitely be running Revit Accelerator for all releases where you're using Cloud Worksharing. If for some reason you turn it off and forget to restart it, Revit will still work fine, but as others make changes to the workshared models you're also working on, you will have to wait for all of those changes to be downloaded every time you open the model, do a Reload Latest, or a Sync with Central. This can be a long wait, particularly for larger models and/or models where there have been significant changes by other users.




Kevin Short
Senior Product Owner
Message 15 of 33
in reply to: Kevin.Short

Thanks Kevin!


I have logged a support ticket as it appears Revit Accelerator is no longer installed on my machine.  And a quick google search does not lead to any significant web page on how to install Revit Accelerator.  All I see is redirects to Revit Server which seems overkill if Revit Accelerator originally installed and ran without any user configuration with 2017 and 2018.  Maybe you know of a good instruction page for just installing Revit Accelerator?


I still have the shortcuts to the folder where it is supposed to reside but the folder and contents is gone.  I believe it was uninstalled with 2017 or 2018 as i previously mentioned but I am not sure.  We will find out!  🙂


Yesterday I also did a complete Repair/Reinstall of Revit 2019 while chasing a BIM360/Revit issue.  That issue has been resolved after some BIM360 resets to my permissions finally took affect.  Sometimes it can take a few hours for the servers to update that stuff...  But Revit Accelerator did not reinstall with Revit 2019. 


Cache files are still active from my BIM360 projects in the cache folder I created on my E drive.  In 2018 before the projects were upgraded, Revit Accelerator was functional and happy with this set up.  Once the projects all upgraded and I removed the older versions of Revit, why would it no longer be active or installed?


These will be great questions to discuss with Revit Support.  🙂


Message 16 of 33
in reply to: bill_hashman

We need to get the Autodesk development team to clarify this, but you do not need to use Revit accelerator when using BIM 360 to host your projects for Revit 2019. The Revit accelerator was specifically developed for use with Revit Server, to address latency issue with accessing a server behind a client's firewall. It is not needed for BIM 360, so that's why it's not available in 2019 (and moving forward with 2020) - you have to use either a specific server name or IP address, and neither of these are available for BIM 360 project that are hosted on AWS.


For more information about setting up an accelerator for use with Revit server, please see this AKN article:


thanks - David B.

David A. Butts

Engineering Technology Manager - Gannett Fleming

Revit Certified Professional/Autodesk Certified Instructor

Revit, AutoCAD Architecture, MEP, Plant 3D, BIM Collaborate Pro Subject Matter Expert

The MEP BIM/CAD Engineer Blog


Message 17 of 33
in reply to: dbutts7

@dbutts7, can you please identify the source of your info? I'd like to have it corrected. Please feel free to PM me.

The Personal Accelerator IS used by Revit Cloud Worksharing in ALL Revit versions including 2019. There is no difference in functionality between projects hosted in BIM 360 Team and Next Gen BIM 360 (Document Management). The accelerator pre-fetches changes (syncs) from the cloud made by other people working on your project. This means that this data is already available locally on your machine when you do a sync. While Revit Cloud Worksharing will work without the personal accelerator, it means that you are taking on a performance hit of downloading the changes during your Sync operation. For optimal performance, we encourage you to ensure that the accelerator is running.


For more info about the personal accelerator see this thread.





Sasha Crotty
Director, AEC Design Data

Message 18 of 33
in reply to: sasha.crotty

thanks Sasha, so that brings me back to my Support Ticket that is not closed yet.  If Revit Accelerator is no longer on my system, then how do I reinstall it with Revit 2019?  Possibly I will completely uninstall Revit and then reinstall it?  Then Revit Accelerator should install properly?  Hmmm...   I wonder...   :_)

Message 19 of 33
in reply to: sasha.crotty

I've sent you an direct email about it. The question came up when Bill asked where the installer for the accelerator is located - but since BIM 360 is not a separate product (aka your thread), the installer isn't listed anywhere as a separate component. That's why I asked for your confirmation.


The main point is that if it's a background service now, does the user even have to set it up? If you've got some direct documentation from the AKN (not a forum post) that addresses how to specifically configure a BIM 360 project to use the accelerator, I'd love to see it.


thanks - David B.

David A. Butts

Engineering Technology Manager - Gannett Fleming

Revit Certified Professional/Autodesk Certified Instructor

Revit, AutoCAD Architecture, MEP, Plant 3D, BIM Collaborate Pro Subject Matter Expert

The MEP BIM/CAD Engineer Blog


Message 20 of 33
in reply to: dbutts7

@bill_hashman, yes a full reinstall should reinstall the accelerator. Unfortunately we don't provide a direct install of just the accelerator. I've also asked the team to look into whether we can reproduce the behavior of an uninstall of an earlier version removing it from your system. 

@dbutts7 , there is no need to configure anything to use the accelerator. It is automatically engaged by Revit when you open a cloud model from the Revit UI. It will then begin to pre-fetch changes for that model and any linked cloud models.

Sasha Crotty
Director, AEC Design Data

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