Wednesday, March 12, 2008

Reduced write performance for Riverbed WAN links when working with AutoCAD MEP 2007 DWG files

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 their customers is a key consideration for Autodesk and Riverbed. Both 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.


  1. Scott - are there other options to riverbed to get around this problem? I went searching for an alternaitve and found this article:

    Do you have any experience with silver peak?

  2. That's a great article. Thanks for sharing. Sorry, but I have not had any experience with silver peak.

  3. I’m the VP of product marketing for Riverbed, and I wrote a lengthy post yesterday on this topic, which can be viewed here:

    Silver Peak has admitted (in a call earlier this week with the TechTarget reporter who wrote that article) that the issue with the AutoCAD 2007 / 2008 .dwg file format is *not* specific to Riverbed and *does* affect all products that use deduplication in their solutions, including their own.

    The only way to determine the degree to which any particular WDS solution is affected by the file format is to do your own testing.

    Remember, the problem is most pronounced with the ISAVEPERCENT (Incremental Save Percentage) set to zero, which forces a complete save, and which causes all the bytes to be scrambled. Using a non-zero value for that setting (like the default value of 50) reduces , but does not entirely eliminate, the impact of the new file format on WDS solutions.

    Unfortunately this is not an issue that can be solved by Riverbed or any other WDS solution provider - it was caused (inadvertently) by the way Autodesk decided to change their file format, including scrambling the bytes on every complete save. Any product that tries to find duplicate data will be affected, possibly to a varying degree, but there is no doubt there is an adverse effect.

    Alan Saldich
    VP Product Marketing & Alliances

  4. thank you very much for great information, hope see and more from
    this website.

  5. Jeff AaronApril 17, 2008

    Hello, my name is Jeff Aaron and I handle marketing for Silver Peak.

    We recently worked with Infoworld to verify our performance with AutoCAD. The results can be found here:

    As we clearly demonstrated, significant performance gains can still be had across the WAN with AutoCAD, regardless of the byte scrambling issue inherent to the latest version.

    We encourage end users to try it out for themselves, and to fully understand how different deduplication solutions work before making any blanket assumptions about what WAN optimization solutions can and cannot do with AutoCAD. To Alan's point, you will likely see varying degrees of results.


    Jeff Aaron
    Director, Marketing
    Silver Peak

  6. Bob GilbertMay 02, 2008

    AutoCAD 2007, WDS and Deduplication - What is the truth?

    As written about here

    Riverbed recently completed a set of tests of AutoCAD 2007 and AutoCAD 2004 with four vendors' WDS appliances: Riverbed, Cisco WAAS, Silver Peak and Blue Coat. The purpose of the tests was to confirm Riverbed's claims that all WDS vendors are affected similarly by the new .dwg file format which scrambles bytes on a complete save, even if no changes are made to a file, and that WDS products are not able to deduplicate the scrambled information within the files.

    Two vendors, Cisco and Silver Peak, have made a variety of claims in press releases, interviews, analyst briefings, blog postings and email campaigns to the contrary such as:
    - "Our customers are not affected by this"
    - "This is a Riverbed-specific problem"
    - "Riverbed is "application-centric" and we are "data-centric" and therefore our appliances are not affected"

    The data shows otherwise.

    The tests were done twice for all four vendors across 64 different combinations of test variables:

    - software version (AutoCAD 2004 and 2007)
    - bandwidth (1 Mbps and 10 Mbps)
    - ISP setting* (0 and 50) in AutoCAD
    - types of changes to the file ("major" and "minor")**

    The tests confirmed that while all vendors could deduplicate AutoCAD 2004, none of the vendors tested could effectively deduplicate AutoCAD 2007 files - in fact two of the vendors sent more data when the file was saved than in the base case. While none of the vendors could reduce the amount of data sent with AutoCAD 2007, they could reduce the time to save files in the new format across the WAN by varying amounts, though not as much as with AutoCAD 2004.

    The results were validated by Taneja Group, a leading storage analysis firm based in Boston, Massachusetts. According to Arun Taneja, principal and founder of the firm:

    "Taneja Group conferred with Riverbed and validated their test methodology. Riverbed has been to the point and transparently forthcoming about these issues to help their customers understand the impact. Clearly, complex file format and application behavior issues present in AutoCAD 2007 impact all vendors in the same way - when test conditions are equal, there simply is no magic pill that makes any one vendor's de-dupe or compression work better with this file format. Moreover, since Riverbed has a broad array of tools to apply to the issue, including mature protocol optimization as well as de-duplication, Riverbed actually performed better under more conditions than the WDS competition, even while AutoCAD's 2007 file format thwarted all approaches to de-duplication. Without a doubt, this issue emphasizes the complexity of storage in the new enterprise, and goes to show that even application vendors must now understand the big picture, including how and where data is accessed and stored in customer enterprises."

    For complete test results and details of the environment, methodology, please contact Riverbed.

    * ISP is "incremental save percentage" or ISAVEPERCENT, a setting in AutoCAD that governs when the application does a complete save. Setting ISP to 0 forces a complete save (and therefore scrambles all the bytes in AutoCAD 2007) even if no changes are made to the file.

    ** a minor change was defined as simply adding text to a file and saving; a major change involved adding a new layout to a drawing and saving it.