Friday, March 14, 2008

AutoCAD 2007 File format and WAN Acceleration - UPDATE

Marie left the following comment on this Blog topic and thought it was important enough to share with all.

Potential for reduced write performance for Riverbed WAN links when working with AutoCAD 2007 DWG files

Published date: 2008-Mar-12
ID: TS1082827

Applies to:
AutoCAD® 2008
AutoCAD® 2007
AutoCAD® Architecture 2008
Autodesk® Architectural Desktop 2007
AutoCAD® Civil 3D® 2008
Autodesk® Civil 3D® 2007

In March 2006, Autodesk changed the DWG file format for AutoCAD 2007 to make it more compact and improve performance for AutoCAD users. Autodesk’s customers widely welcomed this change and almost all AutoCAD users have enjoyed improved performance.

However, Autodesk and Riverbed have recently received reports that some customers using some WAN acceleration appliances, including Riverbed’s Steelhead appliances, have experienced noticeable reductions in write performance when working with files saved in the AutoCAD 2007 “DWG” format. One of the side effects of the DWG format changes is that when users perform a complete save from within AutoCAD (as opposed to an “incremental” save), virtually every byte of the file gets changed – even if zero changes were made to the file itself. The net effect is that writes that would normally affect only “warm” data are actually “cold”, due to the reordering of the data in the file.

Users of Riverbed or other affected WAN acceleration solutions can implement the following immediate workarounds that improve write productivity.

1. Using a feature in AutoCAD called “Incremental Save Percentage” (ISP), and setting it to 50

2. Using a version of the DWG format other than the AutoCAD 2007 DWG format

The performance and productivity of our customers is a key consideration for Autodesk and Riverbed. For this reason, our engineering teams are working together to devise workarounds and are examining potential longer-term solutions. Given Riverbed’s experience in WAN acceleration technology, our joint work may also provide solutions for customers of other WAN acceleration or deduplication technologies, who might be experiencing similar issues with write performance. We will provide information on those developments at a later date.

In the meantime, customers should contact Autodesk or Riverbed customer support with any questions, or visit

1 comment:

Ton said...

Great to see Autocad making changes to increase performance of Autocad itself. It's also great to see that there are workarounds to overcome performance degradation caused by SOME WAN acceleration solutions, but they skip the gain Autocad provided in the new 'DWG' format.

Don't forget that there are also other WAN acceleration solutions that do NOT suffer from this issue, like Packeteer's iShared/iShaper platform. They provide a file-level cache, i.s.o. a block-level cache. The user writes his 'cold' file to his local cache, which happens on LAN-speed. Once the file is saved in the cache, the end-user is done saving. In the background, the 'cold' file is saved to the datacenter. Since it's a 'cold' file, the complete file has to be written to the datacenter, but the user doesn't 'feel' the cold-file save. For the user the 'save' is done once the file is at his local cache.

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